Any blue that is not too green will look very nice. See Houzz Photos under "revere pewter and blue" for examples.

We have a Ben Moore Gossamer Blue in our downstairs bath. It's a very clear blue- really pretty and would go well with gray, I think.

my living room walls are the same color...I love it, I have brought in a rug with a blue in it, I think it looks nice, not sure were you are thinking of adding the blue, rugs, accessories, a subtle teal, or robins egg blue would be great against the gray, here is a picture of my rug, unfortunately you cant see the walls too much

here's a few blues I think are just beautiful, fresh and would work beautiful, of course without seeing the house or design, or style its hard to know exactly.

Oh-- sorry. I thought you were talking about another paint color. :) I think any blue goes well with Revere Pewter, though I agree about the 'not too green' comment above.