Luck is what he was talking about, Burning Thought, crossing fingers that Niko sees Sam before Sam sees him.
With automatic weapons, Niko has greater chance, since the handgun is what Sam does best with, but there's no "automatic only" scenario, so I give it to Sam 10/10. Niko's only shot is to see Sam before Sam sees him (Luck), and luck should not be taken in consideration in a versus. Sam will most certainly see Niko first.