As of my last update, Dave Portnoy, the founder of Barstool Sports, is known for his high-profile sports bets and often shares his wagers on social media. However, the specific amount he bet on Michigan for any particular game or event is not something that can be provided without current or historical data.
Dave Portnoy frequently bets on college sports, including college football, which Michigan is known for. The amounts of his bets can vary widely, from a few thousand dollars to significantly larger sums. To find out how much he bet on Michigan for a specific game, you would need to check his recent tweets, as he often tweets out his bets, or look for updates from Barstool Sports.
Please note that the information could have changed since my last update, and for the most accurate and up-to-date information, you would need to check the latest sources.