I think Gunn and Angel died. I think Illyria and Spike survived. See below for my reasoning.
Like the others have said, Gunn was already dying from loss of blood. The vampire thing, I find unlikely. First, why would a vamp bother with an empty glass? Second, Gunn is great at dusting vamps. Whatever got close enough to kill him, it was probably not a vamp. I'm guessing he fought until he passed out, at which point he was either eaten by something or trampled by the hordes.
As for Angel, I think he died. Think about it. He signed away the Sanshu prophecy. Someone had to remain to fulfill the prophecy, so that means Spike must have lived to be a real boy again. The chances of either vamp surviving without intervention from the powers were pretty slim to begin with. It looks like the intervention all went to Spike, so that's why my money is on Angel dying.
Then, there's Illyria. Illyria is a super-strong God lady. Plus, her "body," such that it is, has been "hollowed out." Unless they chop her in half or decapitate her or something, I think she'd survive. I mean, you could run her through with a sword, but you're not really gonna hit anything vital. Like the vamps, she's just a reanimated corpse. Unlike the vamps, she's a God and she's not allergic to sunlight, holy water, or wood. She's probably got some deep reserves of God power in there somewhere, too, so I'm guessing she would have had the ability to stage her own divine intervention, being divine and all. Even if that's not what happened, I'm not entirely sure she can be killed. I mean, she was held captive in a sarcophagus for thousands and thousands of years, but she didn't "die." Her shell might be able to be broken or killed, but I'm not sure her essence can be destroyed.
If I were Illyria, I would have brought Wesley's little ray gun and retrieved my extra special God power. If the blast was gonna take out L.A., then surely controlled bursts of power from that gun could have seriously thinned the demon hordes.
So yeah. I think Gunn died. I think Angel died. I think Illyria probably survived in some form, but not in Fred's body. I think Spike probably turned into a human thanks to the Sanshu prophecy and high-tailed it to the slayers to inform them that, hey, dragons and other big monsters were ravaging L.A., so could they please get their butts to the front line and save L.A.? I don't think Spike would have survived long, mind you, but I think someone had to survive long enough to get in contact with the slayer army, and I think the Sanshu prophecy is what would have allowed Spike to be the one to do that.