I was under the impression that Canis actually prefers melee range. He certainly would think he has nothing to fear from Luke, as he appears to be wielding a melee version of the Imperial Guards' lasrifle, which isn't that effective against Space Marines. Therefore, he's in for a nasty surprised when Luke manages to trap or otherwise incapacitate his mount, then match him blow for blow in melee.
I think the only part of Canis' armament that can repeatedly resist Luke's lightsaber blows are the Lightning Claws, so it comes down more to who the more strategic duelist is. It can be made abundantly clear that Luke has far more talent than any other Jedi, as with only a few months of training he managed to take on and defeat the second most powerful person in the galaxy, in their preferred style of combat. It took a lot of ingenuity as well, as Luke is shown at being particularly good at hiding in plain sight. Therefore, Canis' ranged abilities, if he has any for this fight (which I doubt) would be useless against him.
Luke could augment his stealth by using the force to disturb objects, making Canis think he's somewhere else, distracting him while he moves for the killing blow. Luke has shown no problem with killing irredeemable foes, so I doubt he'll have any trouble killing a fanatic who burns entire worlds for not worshiping the Emperor.
In a direct melee fight, Canis might have the advantage of speed, though Luke has shown that it will not ever be a direct melee fight for long.