What wins out in the end: instinct or reason? How does Rainsford survive?

Rainsford wins on reason. He is the perfect hero-protagonist. He uses his survival hunting skills to avoid Zaroff. When faced with certain death, he reasons that jumping from a cliff would give him better odds than facing Zaroff's dogs. Rainsford’s survives the fall and, being a strong swimmer, swims to Zaroff's mansion.