Watched some cadet air experience fly a chippie into a cable once. Glider hardly missed a beat, disengaged and landed.
As a glider pilot on a winch launch, your hand is very close, if not actually on the release knob during the whole launch sequence, from the very moment the cable is engaged in the aircraft hook to the normal point of release. The trained reflex if anything goes wrong, is to release the cable. You then stuff the nose down to keep the airspeed up, and depending on the height, land ahead or fly an abbreviated circuit.
The winch launch sequence, including attitudes and speeds, is designed so that at any point during the sequence, you can disengage and land safely. Cables, weak links and other parts of the winch cable arrangement may (and will) break at any inconvenient moment.