I know that many traders use Twitter and many of them follow the tips on Twitter. but for big market like bitcoin. I dont thinking that Twitter has a big influence on the price changes in Bitcoin.
Usually huge investors are having twitter like Craig whom was the latter having post in his twitter account. There is a good OP that has stated that twitter could be a tool for bitcoin market price to go hype. Just take an example of Craig's post about the BCH hardfork. It relatively pull down market price for bitcoin as many where confused on what will happen to bitcoin and sell their bitcoin holdings. So, probably twitter could play important role in bitcoin hype.