It’s a pretty good rule of thumb that when a campaign releases their internals in a general election, they are in trouble. Then again in this case, I see a Marist poll that shows a tie race as well - so maybe this is an exception to that rule.
The Tillis campaign may be releasing the internal as a get-out-the-vote mechanism—if you want to ensure that every Republican and conservative votes, saying that you’re tied is better than saying that you’re up by 1 or down by 1.