(((NikNox))) - I'm so sorry for what you and your family are going through. I was once a nurse, but even I can't tell you how long she has if she keeps it up. It does sound like the alcohol is taking it's toll on her liver and rest of her body and death is a very real possibility if she keeps it up. I've seen people with liver failure have a prolonged and pretty agonizing death, others I've seen go fairly quickly. Most get seriously confused and agitated, as toxins build up, so it might get to the point where your stepdaughter doesn't need to be around her, IF she shows up for a visit.
I'm glad your stepdaughter has you and is receiving support. I'm also glad you're here, as this has to be hard on you and we are here for experience, strength and hope.
Hugs and prayers,
Amy