YES, it is if you purchase the right brands, which is most of them. For instance, "Carnation" brand is gluten-free. Do an internet search for "gluten-free evaporated milk" and a wealth of informative and trustworthy sites appear that list a practically infinite list of all/any gluten-free brand name products.
No. Unless you buy Organic, which is very hard to find. Most dairy has gluten.
Gluten is a plant product so I'm not sure how it could be in milk and milk products.