I hate to debunk all the hopefuls, and before you all hop aboard the Rage train and say I just don't like angel, I love Angel.
When the JGG (Jolly Green Giant) flew up towards the roof of the tower after the line snapped, They were trying to figure out a way to pick up angel.
Had they had time they could have done 2 things:
1)Gotten close and opened the door letting him get pulled in
2) Gotten as low as they could and have him grab on to the bottom of the chopper like the Zombie did.

While I do believe he is a alive for the Story's sake, There is on major thing that takes away from that hope. The last time they see angel is when they are trying to pick him up from the roof. Seconds later the last RPG sails past and hits the roof. If logic serves correctly; The chopper was as close to Angel as possible and this is the Same side of the roof as the Slack Zipline. I made a thread asking how much damage an RPG would do to a concrete wall with a person behind it.
he general response was the person would be Obliterated. Even if he did survive the blast there is 0 chance that he rappelled down for 2 reasons:
1)he is badly injured, Regardless of how much damage he took from the blast, he was most definitely thrown backwards into Bills New skylight.
2)The Blast most definitely broke the rope at the top of the tower. A small explosion wouldn't have done it. Bu this blast was large enough to be the Tipping point for the tower. Literally.
I think he is Alive. But he did not Rappelle down. Not a chance in hell.