I believe that in the book as a whole Pechorin exercises a lot of free will. He schemes to cause mischief and grief to others throughout the book in order to keep himself entertained. But "The Fatalist" seems to be somewhat different from all the other stories, like Kat said Pechorin already knows that Vulich will die; he thinks it will happen a certain way, but it happens differently i think this is a large indicator of fate. Vulich was destined to die and it happened.