I think it's funny how the debate now (for the most part) isn't whether she will die, as it was when I first created this thread so long ago, but on whether it will be the neck snap or the fall.
Some things to think about...
First, this pic:
Happens right before Spider jumps down onto a different cog than the one Gwen is shown on and casts his web. We then see Gwen holding the web while hanging and looking up (her neck is most definitely NOT snapped).
What we suspect is that this pic:
Happens before the one of her falling and Spidey webbing.
And since we've pretty much proven that this cog that Gwen is on is different than the one that Peter is on when he webs, it means that something happens to cause Gwen to fall off of the cog she is on and Peter webs her from a different cog.
But now Peter would be a little preocupied trying to haul Gwen up, and Gobbie would take advantage of this.
So I've surmised that Gobbie attacks Peter (while he's holding the web) and they topple down to the same cog that Gwen was previously on, which is shown here:
The petina on this cog matches identically to the one Gwen was on. And the web either gets dropped or cut by Goblin (he's holding some sort of hilt looking thing in his left hand).
Either way, it makes sense for Spider to fight off Gobbie, to then rush to look over the side of the cog to find that Gwen is gone. That would mean that she fell to her death.
It's hard to believe that Peter drops the web (or it gets cut) and he then has time to fight off Goblin and then re-web Gwen, snapping her neck.
The only drawback that I see to this is that Peter holding the lifeless body of Gwen would be very powerful and if she fell from too high, that would be a bit messy. They wouldn't do that, I would hope.
I guess if she fell from a height that would kill her, but keep her body intact, that might work, but that seems a strech from what we've seen so far. Maybe that new pic of Gwen falling horizontally supports this.
I think many are still hoping for the neck thing, but I'm leaning towards the suspense of her falling (Peter losing hold of the web).
Oh, and above some were talking about Peter's costume being damaged in Times Square but not being damaged at the clock tower. Haven't we already prooved that Electro will end up at Ravencroft after Times Square, where he will get "amped up", which would give Peter some time to fix his costume (or put his spare one on) before the final battle?