The narrow gate is the path to eternal life - which means not tasting death at all as Enoch and Elijah never tasted death. These are the few that have found it thus far, and this was before the Crucifixion. If it meant dying first, then saying that it is eternal would be a lie.
The broad gate is all those who die and need to be resurrected.
There is a reason why it is written:
Except ye eat the flesh of the Son of Man, and drink HIS blood, ye have no life in you. This is talking about eating the WORD, undiluted, not the ritual of communion. And it saying from the Son of Man. the GOD in HIS incarnate Manifestation is not the Son of Man. HE is the GOD who created Man. Which Man is HIS father? The Son of Man, is the Son of Lord Adam H.E, the Son of GOD, and that is Elijah.
Thus, Elijah will have the restored Gospel, because he is the one to restore all things, the restitutioner and the people which Hearken unto his voice shall be saved from death, while the ones that dont will be crushed at the return of GOD the Son.
We are supposed to be Spiritual People as Christians, all we do in this Earth earns our office in Heaven. If you chose death, then you will be resurrected and will inherit the new earth. IF you choose life, and hearken unto this voice, then you will make the 3rd Heaven Eden. However, all children of the kingdom are saved from the lake of fire, and will return to their home, Heaven.
Read: Acts 3:19-23, Malachi 4:4-6, Rev 10:7, John 16:12-15 1 Cor 15:50-58, John 8:51-52, Ezekiel 37.