Social media shares, likes and plusses will not rank your website. Shares, plusses and likes are the result (not the reason) if your website is already ranked in google.
Tested on over 100 domains: 1. With or without 1000 real plusses from publications on gplus: no ranking changes. 2. With links from 50 middle quality domains (Majestic trust 5-10) = 200-500% ranking boost measured with +Serpstat
So, wtf you do in social media? Be sure, it's not seo. Yes, social media will help your site's popularity and if site is in some social niches, you can get some links. But if your website is business site or online store, you will be disappointed - the number of links will be really ~ 0.
Ping +Nikola Minkov +Peter Nikolow +Omi Sido +Moz