"Among political science scholars"
I don't think there's a consensus here, or that any study has been done that quantifies the opinions of 'experts'. And as an ordinary person I would say that Trump is not a populist. But I do think he exposes and enhances the anger felt by ordinary people who've grown to distrust the government, and government officials.
Connection between successful entrepreneurs and populist leaders
I don't think there is a connection, to be frank. Bernie Sanders was a populist leader, he was not a successful entrepreneur. Obama, Reagan. These candidates/presidents were not hugely successful entrepreneurs, but they were populist leaders.
Populist leaders are successful because they sow distrust in current government policies/officials (think Obama's 'change', 'yes we can' or Trump's 'drain the swamp' messages). They are perceived as honest, trustworthy or authentic people by their supporters. They are typically anti-establishment, which boosts their 'I will be the change you're looking for' message.
Those are the typical qualities of a populist leader, regardless of their economic class. Specific to successful entrepreneurs, there's an added perception of being able to improve the economy, knowing how to make good deals, cutting waste and making government more efficient (With Trump and Republicans, there's an added perception that businesses are more efficient than public entities. Therefore a businessman would make government programs more efficient).
This is evident by the fact that American's don't like Trump. Historically one of the worst polled presidents in history... yet when people are polled on "his" economy - he polls much better. (-18 NET approval rating vs. +2 NET rating on economy)
There is no connection between Populists and Successful entrepreneurs. But when ordinary people trust and vote for successful entrepreneurs, their decision might be further validated by the perception that the economy will improve, and government will run more efficiently with a rich businessman in public office.