Can Wolverine kill Thor?
They've already fought a few times in the comics. Wolverine landed several direct shots on Thor and although he was able to cut Thor, they were moderately shallow cuts. None of them were deep or serious despite the fact that they were direct hits delivered with full-strength and intent from Wolverine. Towards the end of the fight Thor started to bleed pretty good but only after repeated strikes from Wolverine. At which point Thor got serious and knocked Wolverine out.
In short, yes, Wolverine can kill Thor if Thor lies there and does nothing. Wolverine can cut Thor's head off but it will take a number of direct strikes to do so.
If Thor is fighting back then not a chance. It only takes a few hits from Thor to knock out Wolverine whereas it will take a couple dozen hits from Wolverine to take out Thor.
It's like saying a sword can cut wood. But try cutting up a fully grown tree with a sword and it will take you quite a number of strikes before you can do significant damage to the tree.