It is very hard to tell with another person, they have to care about their behavior for it to change. My brother was an alcoholic and we (our parents and I) did get many of the calls from police stations about driving intoxicated and worse things (fell up a flight of concrete steps with a glass in his hand, tore up his face and then bled all over his girlfriend's white couch; that was the last straw for her -- he still wears a beard to cover up the scars).

I do not know how old your brother is; if he is in his 20s/early 30s I'd just not associate with him, mayhap he'll meet someone he wants to change for, start a family with, etc. It could pass or it could get worse, no way to tell. If he is talking to you though I'd act disgusted and say something like, "Dude, you stink of booze" or something and wave your hand in front of your face to fan away the fumes. Make sure he knows you do not approve or want to be with him when he smells like that.