Do social media impact SEO? This question is very difficult to answer. And only a few have tried for one major reason: it is often a subject of discords between the various web marketers and SEO professionals. In any case, it is generally agreed that even if social media do have an impact on SEO, it is only indirectly.

Yes, social media have an impact on SEO ...

SEO is a set of practices and tools that aim to improve the ranking of a website in search engines, and primarily in Google which accounts for nearly 99% of all traffic. Well, appearing in search engines is a guarantee of visibility. But do social media help gain visibility?

In theory, yes! Indeed, social media would seem to help improve the visibility of a site, its popularity and generate qualified traffic. Social media also make it possible to increase the number of referent links, even if they are no follow links - that is to say links whose interest is less important. Anyway, it is well known that the popularity of a site, its traffic and the backlinks it enjoys are positive signals for Google. So, we can say that developing one’s presence on social media improve SEO.

... But intrinsically, SMO does not impact SEO!

But when we ask ourselves whether social media has an impact on SEO, we are mainly trying to answer the following question: do they have an impact in themselves, regardless of the inherent effects of the mere presence of a brand on social media (linkbuilding, traffic acquisition...)?

Well, according to Matt Cutts, an absolute reference in SEO matters and a spokesperson for Google, no! Social Media Optimization (SMO) does not impact SEO for the simple reason that social media are not taken into account by Google's algorithm.
So, if we talk about the impact on SEO it can only be indirect, since social media have no effect, strictly speaking.