First week bump will be comparable with Uncharted 2's. I don't know how much that was, 10K 20K?
But in the long run, like with all AAA exclusives, Alan Wake will help to sell tens of thousands of consoles, because it strengthens the high quality exclusive library of the console, it's just that the extra console sales will come over such a long time (months) that it's impossible to trace them in weekly sales trends.
Also, most people don't decide to buy a console based on only one game, but on at least a handful, but in a part of those decisions Alan Wake (just like any other great game) will be the tipping point for some people to go out and buy a 360.