I think that social media does influence bitcoin's growth a lot as it makes bitcoins know among people and also helps spreading knowledge about them as how they work and all that.People would be get interested and will try to invest in them to gain profits from bitcoins which would contribute to growth of bitcoins.And social media gets to lots of people's homes and would cause to bitcoins growth.
Social media is playing the role of backbone in connecting people together and spreading awareness about things that are there for the welfare of human beings. I am pretty much sure that if this social media is used in bets possible way, it can increase bitcoin investors to enormous level within few days and it is already doing the job but not on large scale. In short, we can use social apps and sites for this purpose.