Matt Cutts has indeed confirmed that social media links play a relevant factor in search ranking and the links are used as a signal on site influence. It is stated in the YouTube clip below that not any Twitter or Facebook link is a ranking factor but links from “influential” profiles may indeed give you some nice link juice.
So what exactly does influential mean?
Influential profiles are user profiles that have a good reputation. Maybe someone who is re-tweeted a lot or someone on Facebook with a heavy following. How Google actually determines if someone on Facebook is important or not is still a mystery, but the outlining factor is that links from bots and spammers may not be your best option. Google will only use links from public profiles that are crawlable so no links from private profiles will count.
Can I just follow anyone? Will that count?
Google will look at the people who follow you as well as the people you follow as an influence factor. Following spammers or using bots will not count. Google is always about quality (A golden rule in Googles book) so don’t try to abuse the system. Get yourself some genuine followers on Twitter and Facebook and start producing material that is worth reading… bottom line
How does this affect SEO?
Social media links are just one of the factors in search rankings and believe me there are hundreds of factors. I would not use this as a mandatory factor but rather as a bonus factor if you can. Not every company needs a social media presence. If you offer services to customers then you may want to create a profile. If you are a celebrity (even if self-claimed) then social media profiles are a must. The more people talk about you and link to you in the social media platforms the better it influences your ranking.