The first thing we should take note of is that the New Testament was first written in ancient Greek; and in the Greek, χιλιάς chiliás = a thousand (one thousand); and every time the word "thousand" appears in Revelation chapter 20, it's a translation of the Greek word χιλιάς [ chiliás ].
A thousand (one-thousand): χιλιάς chiliás.
Two-thousands: δισχίλιοι dischílioi (example Mark 5:13).
Three-thousands: τρισχίλιοι trischílioi (example Acts 2:41).
Four-thousands: τετρακισχίλιοι tetrakischílioi (example Matthew 15:38).
Seven-thousands: ἑπτακισχίλιοι heptakischílioi (example Romans 11:4).
Five-thousands: πεντακισχίλιοι pentakischílioi (example Matthew 14:21).
Five thousand: (five times a thousand) Five (πέντε pénte) times a thousand (χιλιάς chiliás, one thousand) = pénte chiliás, five thousand (example Acts 4:4).
Ten thousand: (ten times a thousand) Ten (δέκα déka) times a thousand (χιλιάς chiliás, one thousand) = déka chiliás, ten thousand (example Luke 14:31).
Ten-thousands: μύριοι mýrioi (example 1 Corinthians 4:15).
Twelve thousand: (twelve times a thousand) Twelve (δώδεκα dṓdeka) times a thousand (χιλιάς chiliás, one thousand) = dṓdeka chiliás, twelve thousand (example Revelation 7:5).
Twenty thousand: Twenty (εἴκοσι eíkosi) times a thousand ((χιλιάς chiliás, one thousand) = eíkosi chiliás, twenty thousand (example Luke 14:31).
Fifty thousand: Five (πέντε pénte) times ten-thousands (μυριάς myriás) = pénte myriás, fifty ten-thousands (example Acts 19:19).
Thousands: μυριάς myriás (example Acts 21:20). It's also used for ten-thousands, and for an innumerable number, for example:
Revelation 5:11
"And I beheld, and I heard the voice of many angels round about the throne and the beasts and the elders: and the number of them was ten-thousands (μυριάς myriás) times ten-thousands (μυριάς myriás), and a thousand (χιλιάς chiliás) times a thousand (χιλιάς chiliás)".
Every time the word "thousand" appears in Revelation chapter 20, it's a translation of the Greek word χιλιάς [ chiliás ] - one thousand only.
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The second thing we should take note of, is that Revelation chapter 20 verses 1-3 clearly speaks of Satan being bound and locked up in the bottomless pit:
"And I saw an angel come down from Heaven, having the key of the abyss and a great chain in his hand. And he laid hold on the dragon, that old serpent, who is the Devil and Satan, and bound him a thousand (χιλιάς chiliás) years. And he cast him into the abyss and shut him up and set a seal on him, that he should deceive the nations no more until the thousand years should be fulfilled. And after that he must be loosed a little time."
Yet in his letter to the Christians in Corinth, Paul states, "But if our gospel be hid, it is hid to them that are lost: In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them." (2 Corinthians 4:3-4).
So is Satan bound (or partially bound, or restricted) right now, and has he been over these last 2,000 years?
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In order to answer this question, the third thing we should take note of, is that Revelation chapter 12 speaks of Satan's ability to accuse the brethren before God having been completely destroyed; and we know this is by the cross of Christ because we are told that "they overcame him because of the blood of the Lamb, and because of the word of their testimony. And they did not love their soul to the death." (Revelation 12:11).
Therefore Satan, the accuser, had no legal right to appear in the court room anymore.
Immediately after this we are told that the devil has been cast out of heaven, and has come down to the earth and the sea "having great wrath, knowing that he has but a little time." (Revelation 12:12). We are then told about Satan going to war against "the woman" who had given birth to the Messiah, and then against "the rest of her seed, who keep the commandments of God and have the testimony of Jesus Christ." (Revelation 12:13-17), which of course, refers to Satan's war against the churches of Christ.
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The fourth thing we should take note of, is that both Jesus and His apostles taught, by implication of the things they said to the churches, that Satan is very active in the world:-
In Revelation 2:12 Jesus tells the church at Pergamos, "I know your works, and where you live, even where Satan's seat is. And you hold fast My name and have not denied My faith, even in those days in which Antipas was My faithful martyr, who was slain among you, where Satan dwells."
In Revelation 2:9-10 Jesus tells the church in Smyrna, "I know thy works, and tribulation, and poverty, (but thou art rich) and I know the blasphemy of them which say they are Jews, and are not, but are the synagogue of Satan. Fear none of those things which thou shalt suffer: behold, the devil shall cast some of you into prison, that ye may be tried; and ye shall have tribulation ten days: be thou faithful unto death, and I will give thee a crown of life.".
In his letter to the Christians in Corinth, Paul states, "But if our gospel be hid, it is hid to them that are lost: In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them." (2 Corinthians 4:3-4).
In Ephesians 6:11-12 Paul tells the Christians in Ephesus to "put on the whole armour of God, for your being able to stand against the wiles of the devil", and then continues to say, "because we have not the wrestling with blood and flesh, but with the principalities, with the authorities, with the world-rulers of the darkness of this age, with the spiritual things of the evil in the heavenly places".
In Acts 26:17-18, we read of Jesus telling Paul that He was sending Paul to the Gentiles ""To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me."
In Acts 5:3 we read that Peter said to a man named Ananias, "why hath Satan filled thine heart to lie to the Holy Ghost, and to keep back part of the price of the land?"
In Romans 16:20, Paul tells the church in Rome that "And the God of peace shall bruise Satan under your feet shortly."
In 1 Corinthians 5:5 Paul tells the church in Corinth to deliver the person who had sinned grievously unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus."
In 1 Corinthians 7:5 Paul says to the married couples in the same church, "Do not deprive one another, unless it is with consent for a time, so that you may give yourselves to fasting and prayer. And come together again so that Satan does not tempt you for your incontinence."
In 2 Corinthians 2:11 Paul tells the same church to forgive the person who sinned "Lest Satan should get an advantage of us: for we are not ignorant of his devices."
In 2 Corinthians 11:13-15 Paul refers to teachers of false doctrines who sought to beguile Christians as "false apostles, deceitful workers, transforming themselves into the apostles of Christ", and then goes on to say, "Did not even Satan marvelously transform himself into an angel of light? Therefore it is no great thing if his ministers also transform themselves as ministers of righteousness, whose end shall be according to their works." (2 Cor 11:14-15).
So Paul was calling the teachers of false doctrine "ministers (servants) of Satan".
In 1 Thessalonians 2:18 Paul tells the Christians in Thessaloniki that he had and those who accompanied him on his journeys tried to come to them, "but Satan hindered us."
In 1 Timothy 5:15 Paul says that some Christians "have already turned aside after Satan."
In 1 Timothy 3:6-7 Paul says that anyone desiring the office of a Bishop should "not a novice, lest being puffed up he may fall into the condemnation of the Devil; and it behoveth him also to have a good testimony from those without, that he may not fall into reproach and a snare of the devil."
James tells Christians, "Therefore submit yourselves to God. Resist the devil, and he will flee from you." (James 4:7).
Peter tells Christians to "Be sensible and vigilant, because your adversary the Devil walks about like a roaring lion, seeking someone he may devour; whom firmly resist in the faith, knowing that the same afflictions in the world are being completed in your brotherhood." (1 Peter 5:8-9).
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Over and over again, the activities of Satan in the world, whom Paul calls "the god of this world hath blinded the minds of them which believe not," is referred to in the New Testament, and Christians are warned and exhorted to be aware of this, and of the wiles of Satan, and to resist him.
In stark contrast to this, not once - not ever - does the New Testament outside of Revelation chapter 20 speak of Satan being bound, nor "partially bound" by having his activities in the earth restricted (any more than his activities in the world have always been restricted to an extent by God, from the time of the fall of Adam onward, throughout the Bible, where many times we read of cases where the activities of Satan in the world were restricted).
Therefore in my opinion, the only Biblical conclusion we can come to regarding the one thousand year period written about in Revelation chapter 20, is that this period
has not yet come.
In my opinion, this should not be surprising to any Christian who reads the book of Revelation and learns from the Revelation that at the time the Revelation was penned, "the beast" (which the Revelation states will ascend from the abyss and be defeated by Christ at the time of His return, and then be destroyed by Christ in "the lake of fire burning with brimstone") "was" (existed at one time), "is not" (does not exist anymore), "and will ascend out of the abyss, and go to perdition".
The Revelation teaches that Satan will likewise be destroyed in the lake of fire after a thousand years - where the beast and and its false prophet (already) are.
In my opinion any eschatology ("end-times theology) presented by any church which teaches that Satan is (already) currently bound
in some manner, is therefore patently false, and is probably based on a theological castle of sand built on the sea's side of the high tide mark.