I'm not sure on a technical standpoint, but I'd imagine an hour of play could amount to a lot. Depending on what mode you're playing, you could be loading in 64 different players, all with different weapons, equipment and skins, plus you have the map, where terrain is being destroyed, audio, etc, I'd imagine atleast a gig for an hour of playing. There's a lot being loaded in and trying to run in the background during the match.
Sorry I couldn't give you a clear answer. Your best bet would be to check how much data you have, play for an hour and then check to see how much you've used.
