Did I miss something?
They haven't said shit about FF7:Re.
Sure, there's all kinds of speculation (i.e., it will be timed-exclusive, like ROTR, or Sony is helping to fund/develop it, so life-time exclusive, etc.), but nothing concrete at this point. Kagari mentioned that, from what she'd heard, it would be a similar situation to Street Fighter V, but yeah... nothing officially announced yet.
I'd rather go with the official word and not rely on insider information myself. It was announced as "First on PS4," suggesting timed exclusivity, and Sony has never had an issue in the past with their 3rd party console exclusives having their PC counterpart mentioned to some degree. The only way I don't see the game coming to XB1 is if the game is coming to Nintendo's next console, and Square simply can't announce that port for obvious reasons.