it Seems that Kingdom Hearts III has at least 80 hours of content. So every 2 hours of content are equivalent to 1 GB. On the other hand, you must bear in mind that the game also seems to include the corresponding improvements of PS4 Pro.
Kingdom Hearts III will be available January 29, both on PS4 as on Xbox One. To know more about the game, we invite you to read our impressions in the following link.