Blacking out does not kill you.  It merely means you do not have enough bloodflow to your eyes/visual cortex for them to function correctly, at that time.

There are several techiniques pilots use to boost their G tolerance.  Using an inflating G-suit and coordinated breathing and muscle contractions will allow most pilots to withstand a 9 G turn.

Think about riding a roller coster (especially in a tight turn), then multiply by 3 or 4.  You get "pressed" against your seat or straps with quite a bit of force.