I don't think it will do well. First, you have all the D&D fans who are upset at WoTC over the OGL issues. So some of those fans aren't going to support the movie. Then you have D&D fans who probably feel that the movie isn't true to D&D and it's just a typical fantasy movie with a D&D skin. Basically, just a normal Hollywood movie with some D&D Easter Eggs and so they won't support it.

Then you have non-D&D people (normies, such as myself) who have only heard of of D&D and who will go see the movie because of the casting or out of curiosity, but there aren't enough of those people to really give the movie the support it would require to succeed. For myself, I like Chris Pine and the movie reminds of me of other comedy/adventures that I have watched and enjoyed, but this isn't something I would go to the theater to see. I'd wait for the DVD or streaming options to become available.