"What are the Gophers going to have to accomplish in Big 10 play to get to the NCAA's?"
To feel completely secure heading into the Big Ten Tournament, I think they need to be 11-7 in the Big 10 (that would be 20-10 overall). I wouldn't advise going 9-9 like they did last season, and even 10-8 could be dicey if they don't have a win or 2 vs. Purdue & Sparty.
I'm not worried about Butler at this point. Yes, they've lost more games than they're accustomed to, but they've played a difficult schedule (current SOS rank is #12). The four teams they've lost to (Clemson, Georgetown, Minnesota, UAB) all are currently in the top 62 of the RPI, and I wouldn't expect any of 'em to drop much as the season progresses.
And it's not like they haven't beaten anybody. ... Northwestern, Ohio State & Xavier are all good clubs. I'm confident the Gophers' win over Butler will be a good one to have on Selection Sunday, and it needs to be because it's all we'll have outside of conference play, unless beating the MEAC champ (Morgan State) on your own court counts for a lot (which it won't).