Some things I consider facts:
1) the stadium will be loud. It always is.
2) the stadium will never be 100% full at kickoff. Some people just aren't able to get to their seats on time and some people are tailgating.
3) many fans that go to the games visit this message board. All you have to do is read their posts on here. I don't know the percentage but many see the games and come here to discuss.