I am a Guillain Barre Syndrome survivor, I was paralyzed from the neck down in an era where medicine for this was almost experimental. In my case, I could have died, or I could have had a partial recovery, or a full recovery, they never know. I know it isn't cool to say anything mushy on vital, but I 100% believe having positive influences around me helped me steer my body (nerves) to heal. I had doctors bringing in folks who have gone through the same thing with positive outcomes coming in to talk to me, family visits, good nurses, just good vibes all around at a time where it is very easy to throw out an anchor and drag yourself into the ground.
I know all circumstances are different, but bring your loved one as much positive energy as you can. Let them know of folks who have been through the same situations who made the most of it, prove to them that it can be OK and give them hope. I will never forget a guy coming in to see my as I laid there in the ICU, his face still paralyzed on one side, and would be that way likely forever, but the guy was built like a rock, found faith, and was so happy to tell me if I tried, things could be OK (like he was). Reassurance and hope can make miracles happen.
I am sorry for your loved ones struggles, good on you for doing what you can.