I once read a while back that Google Search algorithms considered the # of facebook likes and tweets for a content page when calculating its Search ranking. I've tested this for a few months now and can't confirm this is true, but it does seem like it is making a difference. It is tough to make a fixed conclusion since AB testing can't be applied to this scenario.
OK. I mentioned that as I think I remember watching an SEOMoz video where they mentioned FB shares and tweets affecting SE results.
But I don't think it happens actually. Lets say people like posts without coming to the site. Then will it increase the SEO ability? If that we can say people to like our posts.