I don’t have the means (or time or interest) to do this analysis myself, but it has been claimed that half that accounts’ tweets are him personally and the other half are a team: http://varianceexplained.org/r/trump-tweets/
It’s already been documented that there is a Twitter guy who works closely with Mr. Trump who originates most of the tweets and then gets approval to send them. It was kind of a big deal because he has his own office very close (physically) to the Oval Office. There was a profile of him done a few years ago. I think it was on CBS News.