Okay, first off, from what Trump said it’s obvious that he was aware that Andrew Jackson was dead before the Civil War. (Which really wasn’t a civil war, but that’s a whole nother discussion.) And while I don’t know that Trump was talking specifically about the nullification crisis, state-federal issues were very much a problem during Jackson’s tenure.
Second, slavery was the issue that pushed the states into war, but it was simply the most volatile aspect of a widening rift between north and south over diverging economies and cultures. The two were going to continue butting heads and it’s possible they might have split anyway, but absent slavery it probably wouldn’t have turned into a bloodbath.
Third, he’s dead wrong that a strong leader could have prevented the war. In fact, it was the election of a strong leader that touched off the war. Previous presidents had been compromising nebbishes and that was why the uneasy peace continued. Maybe if they’d managed to keep dithering until industrialization made slavery unprofitable, it could have died a peaceful death. Maybe. But no, Jackson neither could nor would have prevented war.
Trump’s right about the way Jackson’s wife was treated in the press, though. They literally hounded her to her grave. I notice that part of the interview hasn’t been reported much in the press, probably because they’re so gleeful about savaging Melania. Hard to blame Trump for identifying with that one.