I don't have hard numbers but the city has been throwing around the 500k+ figure for a while... just look around downtown, there are acommodations and attractions that blow away what happens in Speedway.
Sounds like they're expecting 150k here Superbowl weekend. I guess more may come in go over the course of the week... like locals going down there this weekend to check things out. I saw something about there being 150k visitors in town and only 25k restaurant seats downtown and 700 cabs. Things will be busy the weekend of the game!
Street Team Update! | Indianapolis Super Bowl Highlights
The stadium will hold about 68,000 for the game (normally 63,000 IIRC), making it the 4th smallest ever.
http://www.indystar.com/article/201...012-Headlines-Game-should-among-smallest-ever