I might be drunk, but I’m not crazy.
酔ってるかもしれないが is called い抜き言葉. The standard form is 酔っているかもしれないが. You can use い抜き言葉 for casual conversations, but don’t use it in writings.
気は確かだ is a frequent expression, meaning “be sane”. For example.
今はつらいかもしれないけど、気を確かに持ってね。= “Hang in there and don’t get desperate even if you are having a tough time now.”
気を確かに持つ is a frequent idiom. It literally means “to hold a rational mind firmly” (= to keep your sanity).