Yep! Social media is a great tool for digital marketing. And by advertising bitcoins you make more people invest in it, so in that way it has influence on bitcoin growth 
Since using social medias nowadays are getting more popular, it is usually used to advertise and promote something and this is probably where bitcoin is mostly discovered.
Yes social media plays an important role in the development of bitcoin from the starting stage to now but some people are still don't know about bitcoin and it's good features and we need to teach them more in social sites .