The NFL has generally done a good job of keeping important revenue information under lock-and-key. We know a decent amount because the Green Bay Packers' unique ownership structure requires they disclose their financial statements. However, it leaves a lot of guess-work. Even when Forbes is doing their annual franchise valuations, it's based in large part on educated guess work.
However, later this month, we might get a peak into another franchise's financials. The New Orleans Saints ownership is in the midst of turmoil due to family squabbles. Benson and his first wife adopted three children, and one of them was expected to run the Saints after Benson.