I went through something similar. I was on the ventilator for two weeks. I ended up getting a tracheostomy (hole cut through the neck to open a direct airway). It's to take your brother off of the ventilator and will get oxygen through his trach. They are trying to move him along. If he is nonresponsive, I would make sure you have a neurologist run an EEG test to make sure he's 100% brain dead before you make any decision. This decison will impact your family no doubt. If he fails his EEG test, the doctor will suggest pulling him off life support, nursing home, or 24/7 care provided by family only if he has a trach and not on vent.
I was on life support for two weeks. My wife made the decision to take 2/3 of my right lung out and trach. If you haven't already done so, I would have your church clergy visit your brother in the hospital for prayer. If needed, hospitals have clergy on staff to assist as needed. My prayers are with you. I've been there and made it back. Don't give up hope.