In all likelihood, he has no role in admissions and in the unlikely event that he does have some role, he'd need to recuse himself from any discussion of your application.
The only thing he could do if you contacted him is to try to find a colleague who is on the admissions committee and ask that person to put in a good word for you. This labels you a "special interest" of Dr. So-and-So, Depending on how good your application is and how important Dr. So-and-So is, you may get a courtesy interview but that is a courtesy and seldom results in an offer of admission (it is being done so that the adcom can tell Dr. So-and-So that every courtesy was extended to you). In some cases, when I've been the adcom member reached out to, I've been sent a message back from the Dean of Admissions telling me to point out to the faculty member making the recommendation that the average MCAT and GPA of those we interview are x and y and that only a small percentage of those who apply are interviewed. The person usually gets the message that their candidate will not make the cut due to much lower than average grades and scores (without disclosing the applicant's grades and scores).
