Twitter is just a part of media like print / electronic or social media including Facebook; linkedin ; You Tube etc. And each type of report on any type of media has effect on the price of bitcoin. When there are positive news the price goes up and in case they spread negative news then the price falls.
That is true, I mean, much like other social media platforms where people go in and spend most of their time these days, it presents a medium where people can market and introduce to many others whatever thing, or in this case, business venture they are trying to advertise. Comparable to Facbook, Instagram and other similar platforms, it has been a big part of many businesses these days.