It's my topic.
The fact that everything in the Bible supposed to be said by Jesus is really only hearsay doesn't bother you, I see.
Does it bother any of you other guys?
I don’t know that bothers me is quite right. But when you read the Gospels you do have to realize that it’s not based on video tapes or short-hand. ViaCrucis gave a summary. There’s been a lot of work on this issue over the last hundred years or so. I think we have a pretty good sense of Jesus’ main teaching. I wouldn’t place too much weight on a single saying though, and particularly not from John.
Did Jesus really say John 3:3? I wouldn't bet too heavily on any one saying. But when interpreted as Via Crucis did it's consistent with his message as we know it.
That particular verse actually has a better claim than much of John to be original. Quoting the comment on it from the Word commentary on John:
"Frequently v 3 is viewed as a Johannine development of Matt 18:3 (cf. Mark 10:15), or a logion similar to it but independent of it (Dodd, Historical Tradition, 359). Yet a saying similar to vv 3 and 5 was cited by Justin: ἂν μὴ ἀναγεννηθῆτε οὐ μὴ εἰσέλθητε εἰς τὴν βασιλείαν τῶν οὐρανῶν (Apol 61); since Justin shows no other knowledge of our Gospel, the logion evidently circulated freely. It is likely that the Evangelist found the saying in an earlier source (Becker thinks that both vv 3 and 5 were current before the Evangelist, who commented on v 3 in v 7 and on v 5 in v 8, Johannes, 134). The concept of being begotten from above is not a simple translation of becoming as a child, but an adaptation of the Jewish hope of a new creation. The Jews became familiar with the application of this concept to people, even in noneschatological contexts (e.g. God is said to make men “new creatures” when he heals them of their infirmities; Str-B, Matthäus, 420–23), but in the tradition stemming back to Jesus the eschatological element was constant. In Matt 19:28 the familiar βασιλεία is replaced by παλινγενεσία, “regeneration,” Matthew’s equivalent of “new world” or “new age.” The LXX renders Job 14:14, “All the days of my service I would wait, till my release should come,” ὑπομενῶ ἓως ἂν πάλιν γένωμαι, literally, “I will endure till I ‘become again,’[bless and do not curse]” i.e. until I live again through resurrection; πάλιν γίνεσθαι is a verbal form of the noun παλινγενεσία. While 1 Pet 1:23 repeats the verb “begotten anew” of Christians (ἀναγεγεννημένοι

, Paul prefers the category of new creation (2 Cor 5:17; Gal 6:15). Titus 3:5 combines the two images; “He saved us through the washing characterized by the παλινγενεσία and ἀνακαίνωσις that the Holy Spirit effects.” The saying in v 3 declares that it is those whom God makes new who will “see” (= experience) the new age. Naturally this saving sovereignty of God will be thought of as coming in the future, as in the Beatitudes of Matt 5:3–12. In the perspective of the Gospel, however, the saving sovereignty has come into being through the redemptive activity of the Redeemer (cf. vv 13–16), and those whom God renews experience it now."
What's being said here is that this verse or something similar appears in a number of different versions of the Christian tradition, at least some of which seem to be fairly independent, and it's consistent with the rest of Jesus message. So even if the wording isn't exact it's reasonable to take it as representing Jesus.
What the commentary doesn't note is that it speaks of entry to the Kingdom of God. That's not language normally used in the Gospel of John. Indeed this is the only passage in John where "Kingdom of God" appears. However that is a key concept in the Synoptic Gospels. That strongly suggests that this isn't something John wrote or found in his own church's tradition, but that it goes back to an earlier source.