Solid question. I had to mull this one over for a bit. In Zaroff's opinion, yes, he does give his prey (victims?) a fair chance to survive. Zaroff will make sure that his human prey are in top physical condition before beginning his hunt. That seems fair. At least he gives them a chance to actually be physically capable of running. I also assume that he gives the prey at least a knife, because that is what he gave Rainsford. Zaroff also gives each man a choice: be hunted for three days or let Ivan whip them to death. The story tells the readers that most men opt to be hunted. Whipping is a guaranteed death, and being ensured good physical condition and a weapon sounds like a far better choice.
The problem is that Zaroff still holds huge advantages over his human prey. It is not a fair chance. Zaroff is an expert hunter. It's his island, so he is intimately familiar with where everything is, including where his prey is most likely to go. Plus, he is also experienced enough with the island to know what looks normal and what has been tampered with by another human. Zaroff's weapons are also completely overpowered compared to his prey's weapon. Zaroff gets a gun. Rainsford gets a knife. I'm sure you've heard the saying "never bring a knife to a gunfight." Plus Zaroff uses dogs to help him search for his prey's location. Lastly, Zaroff has a safe location to return to each night in order to become well rested and fed. None of his prey have that advantage.
So no, Zaroff does not give a fair chance to his human opponents.