With all of the experience returning on offense 40 TD's I can see, but no way 50.
There will be even more of an emphasis this season to grind things out in the 4th quarter, which will lessen Beck's TD's.
When you've got 3 guys in the backfield in Brown, Vakapuna and Tonga blocking for them, look for BYU to wear opponents down. The offense will be high octane, but it will also be a very bruising one as well.
50 TD's is quite a stretch in my opinion, but I'm glad Beck has a lofty goal.