The nightclub is liable if you can establish that they served the "drunk guy" when they knew or should have known that he was intoxicated. Having litigated similar cases on both sides, I advise that you immediately retain a very good attorney with experience in this area and also a very good private investigator. You need to know who the guy was, who he came in with, how many drinks he was served, who served them to him, how much he had consumed prior to going in to the establishment, where he had purchased any alcohol prior to going in to the establishment, whether the people in the nightclub knew the guy, how he paid, whether with cash or credit, whether other people purchased alcohol for him, how many people who were there while he was there can be identified and interviewed, how many people who were there made observations as to his consumption of alcohol, his ability to speak, walk, sit, who were his "friends" or other people people he was with, how and why the fight started, and this is the beginning.
You have been injured severely and you need a good team behind you to flesh out what happened. Do not waste time finding a very good attorney because there are also "notice" requirements under which you must give proper notice of your claim in a short period of time after your injury.
The bottom line is that if "the guy was clearly drunk" as you indicate, and if you can establish that he was served alcohol while he was exhibiting signs of intoxication, you will have a very good case. Do not be surprised by the fact that insurance companies do not normally want to pay these claims and that they will fight, and investigate all of the above indicated facts and many more.
I wish you the best, seriously.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Sign up to receive a 3-part series of useful information and advice about personal injury law.