How to use Google Plus for Search Engine Optimisation
SEO and "social media engagement" via Google Plus (Google+) Pages
Google has gradually shifted its main emphasis from traditional websites to "social media", and by 2013 the effects of this shift have become quite noticeable in the search rankings. By "social media", Google means Google Plus (Google+) much more than any other similar system (such as Facebook). Google evidently aims to replace Facebook with Google+ as the predominent web-based social networking medium and they are promoting that by providing important search result ranking advantages to Google+ users.
Important: Your Google Plus page has PageRank just like any other web page and can pass this positive influence on to your website via linking. A high Google Plus PageRank seems not to depend on how many other Google+ users have you in their circles but rather on the PageRank of the Google+ pages that repost (and thereby link to) your content.