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.