I believe he will. As a fan I want him to. As an observer I think it's a great story.
For those unfamiliar with that story, allow me to recap.
CM Punk was a professional wrestler so popular that it would be surprising if you haven't heard of him at some point. After years of wearying travel and disagreements with his bosses, he quit the WWE. When contacted about fighting in the UFC by Dana White, he jumped at the opportunity.
A young fighter - probably looking to make a name for himself - called out CM Punk after a victory, asking the UFC to give him that fight. The deed was done, and CM Punk had his opponent. After a tough go at training where he suffered multiple injuries and was forced to set back the date of the fight on more than one occasion, the fight is finally happening tonight.
Punk trained for a year-and-a-half with one of the best teams in all of mixed martial arts, and despite many thinking a transfer from pro wrestling to MMA was a stupid and even disrespectful act, Punk has been slowly gaining the approval of the community. By all accounts he's dedicated, works hard, and has a chance to be successful.
As I said, I believe he will win. But is that stupidity on my part?
As a fan of pro wrestling, I'm on the man's side. I know the sport is gruelling and populated by talented and tough athletes. I think people who say Punk is being an idiot because wrestling is fake and MMA is real are being tools. There's a lot of crossover. Besides necessary athletic gifts, there is a mental discipline in pro wrestling that must be a great aid to its practitioners in all other endeavors, the fight game included.
The one obvious minus is CM Punk's age. At 37, he's an old dog learning a new trick. With only a couple of years worth of martial arts training, he'll be fighting a guy who's been at it for a decade. That's a big difference in experience.
This would be a tough challenge for anyone. But heaped upon that challenge, due to his fame and previous high-profile career, there is also the pressure to perform and entertain. Punk has been saying all the right things in regards to this and other questions since nearly day one, so I think his head is in the right place.
Hopefully, he remembers to move that head around a lot tonight so he doesn't get punched in the face.
Short Answer: I hope he wins, for the story. I hope he wins because he's an underdog. I hope he wins because he's a journeyman with a lot of experience on the big stage, putting it to a 'punk' kid. I believe he can do it. But that belief is partially based on seeing him raise the WWE championship. If I'm to be objective, having not seen him fight ever before, I'd say this one's a coin toss.