I think if I liked gravy, I'd make it myself, but if you want something quick, the question is not just 'how much sugar is in it', but, 'how much do I eat ?'. If you have a lake of gravy, then that can translate to a lot of sugar, if there's a reasonable % of sugar in there. I think if you need some gravy to get through your meal, it's not the worst thing in the world, but that would be my general rule of thumb regarding anything that has small amounts of sugar in it.