There is no way to know for sure. I have known people who swear it worked for them, but the actual percentage of people who succeed through AA verses other methods, or even just going cold turkey will never be known because of AA's anonymity (the second"A").
Actually and unfortunately the success rate for any program is relatively low. Best guesstimates are between 20-40%.
12 step programs are generally considered to be on the higher end of these estimates.