Husband was diagnosed with end stage liver disease, congestive heart failure, common variable immunodeficiency, ulcerative colitis. How much longer?

Impossible. There are many variables that you don't state (and probably don't know). Even if all the lab values were available, an accurate time table is never possible with human beings. I think you know from your question that each day with your husband now is precious. Try to enjoy what time he has left.