Both times I have taken the Amtrak back and forth between Champaign and Chicago I have been late on both legs of the round trip. The delays have ranged from 1 hour to 3 hours. It should NOT take 5 hours to get from Champaign to Chicago on a train.
Unfortunately as one of those pesky Chicago dwellers who does not own (nor plan on buying) a car, this is pretty much my only way for me to attend U of I football games. Well, I guess I could rent a car for the weekend, but that would be around $100+, whereas Amtrak is $13 each way if you book far enough in advance. As long as the football game is at 2 PM or later, you should make it, since the train is supposed to arrive in Champaign at 10:45 AM. But if you have an 11:00 or noon game, do NOT expect Amtrak to get you there by kickoff (or even halftime in some cases).