The problem, like almost everything that comes out of Trump’s mouth, is that this number is drastically exaggerated. A large number of those followers aren’t potential voters. They are not even people. They’re bots.
The percentage varies tremendously according to who you ask: anywhere between 3.4 and 41 per cent.
I enjoyed the payoff to this paragraph:
Back in the early days of fake followers, the programmers who made the bots often just plucked pictures of people from Google, created a fake name, fake biography, and—voilà—you had a fake follower. But now, to subvert being found out, bots have become incredibly clever, even sometimes becoming indistinguishable from real people. They use semantic analysis to understand what people are tweeting about, and reply with answers that are mostly coherent, which also more or less describes how Trump uses the service, too.
Related: my friend Phil on the user experience of buying fake followers.