It is kinda hard to tell in this picture (sorry bad quality) the striped shirt under the dress completely ties it all together because the stipes are camo!! Which matches just perfectly with the shirt dress. When it comes to the sweater and belt (camo belt shown) I think you could do any shade of a brown belt with a oatmeal sweater of your choice.
I am on a 100% mission to copy this whole look and love Gap a little more for coming up with it. You have got to check out all of their new fall looks, because honestly the looks they show really sell the clothes and are styled better then the individual items. Do you know what I mean? For instance this cashmere drape sweater does not look as cute on the model they have it on as it does here, I was almost so turned off by it but it works perfectly here I was convinced it was just her haha.