Google treats Google Plus content like any other web page. Recently, Dr. Matt Peters and the Data Science team at Moz released the results of their study which measured the correlation between Google+1s and higher rankings. They discovered that Google Plus can improve SEO results, even if no clients use it.
1.) The Google Plus and SEO study results revealed that after Page Authority, a URL’s number of Google +1s is highly correlated higher with search rankings compared to other metrics, including Facebook shares, linking root domains, and keyword usage.