i'm not sure whether it improves our hubs SEO or not, but what it really improves, are newcomers to your hub. It's worth answering question and even making them on topics you know well or would like to know more, because if you make an interesting answer, people wants to find out whether you write interesting hubs to. So in that way they come to your profile, and maybe to some of your hubs. I'm one of those who likes to search for interesting questions and give my opinion.
And i'm sorry, i can't answer the main question here, but i think the answer should be not, because backlinks are to your profile, not exact hub, so it should make sense or if it does, it should be just a little.