The graph shows the candidates close to the best fit straight line except for Cory Booker and Joe Biden. In spite of these two outliers the regression model shows that 51.38% of the variability in the candidates' poll numbers is accounted for by their respective Twitter followings on their campaign accounts.
Looking at the candidates Facebook page followings, a similar but weaker pattern emerges. Biden and Booker are still outliers but there is still a significant positive relationship accounting for 42.41% of the variability. Interestingly Booker was the only candidate to have a net decrease in Facebook followers since September. It remains to be seen how this translates to primary victories this spring.