Will knowing a professor help me get accepted?

interesting question. My guess is, if you don't have a close enough relationship to talk to him about applying it may not help. If you mean it's simply not a working relationship where he could actually be your recommender, you may be able to sit down with him over lunch and see if he is willing to serve as your advocate in the application process. This simply would entail him chatting up the Dean or the adcom about your application and how he endorses your acceptance. Sometimes that can actually go a long way depending on two things: 1) their standing with the Dean and Adcom, and ) how good your application is on its own.