Well, I know that drinking doesnt help with this problem, it sounds like a confidence issue, maybe with his appearence or performance or maybe the two combined, which would affect anyone to some extent.
The best advise I can give, is take your time, lots of reassurance, dont even get to the intercourse stage, just massages, kissing etc, if you think he looks good, tell him, it may take a while but his confidence will build up eventually, and tell him to lay off them beers!...good luck!