Nobody knows for sure. If you're talking about TV deals, I suspect that Big 10 games get higher ratings than Pac 10 games, but don't know for sure. There could be any number of reasons for that: culture, time slots, etc.
If you're talking about a Pac 12 network, I think it would likely make similar money. The big football games are still on the networks and the conference network gets the lesser matchups. Also, the Pac 12 will have more interesting content than the Big 10, baseball, volleyball, etc.
The real reason the Pac 12 will be better off than the Big 12 is because the Big 12 will never have its own network--because Texas won't share and will demand its own network. Thus, the rest of the Big 12 will forever be at a disadvantage to the conferences with network ownership.
That alone shows the massive difference in the revenue potential for both conferences. More network revenue in 12 Pac = more money for everybody vs More network revenue in Big 12(10) = more money for Texas + table scraps for everybody else.