The lots closest to the stadium are all pass lots for season ticket holders, but there are various public lots all over the North Shore that aren't too far of a walk from the stadium. The lot I park in for every game is about a 10-15 minute walk from the stadium and costs $25.
If you don't want to deal with parking, you can of course also Uber/Lyft to and from the game. It also may not hurt to see if there is a shuttle running to the stadium from your hotel if you don't want to do any of that.
If you have any other questions or concerns, just ask and I hope you enjoy your visit to Pittsburgh (though not too much!)