What color shirt should I wear with gray pin stripe dress pants

I think a cranberry color would look great with gray pinstripe. You could probably use pink as well.

Gray is a neutral and as long as the pinstripe is small it is also a neutral so you may wear any color. I personally love green with gray but I also like pink, red, blue, and even black then use colorful accessories.

I would recommend a nice bright yellow. It goes really well with gray. Also purple is good too for paler skin tones (I'm very pale).