Well in Spiderman's case Gwen would've survived if she was caught before. Spidey's web is stretchable so it would have decelerated her fall. It even stretched on catching her but she was too close to the floor and hit her head.
Is that in the movie? This is the image I have in my mind but I forgot that she hit her head. I think that's not the case in the comics IIRC. Instead it's unclear whether her neck was already snapped before she fell, or the late web catch caused the snap.