Grindelwald is described as being extraordinarily convincing, to the point that they had to prevent him from speaking while he was in prison so that he wouldn't exercise his influence on the guards.
He convinces Queenie, who had previously shown no inclination towards dark magic, to join him in less than a minute. After he gives a brief speech, she voices no objection to joining him (in spite of realizing who he is) and seems unswayed by Jacob Kowalski’s objections. Indeed, she seems virtually bewitched. On the other hand, Jacob seems largely immune to his influence at the rally (apart from being visibly distressed by Grindelwand's prediction about another war).
He also seems to know exactly what to tell Queenie to be as convincing as possible, even though he's apparently not gifted at Legilimency (or, at least, he's later seen consulting Queenie's skills on the matter).
Is Grindelwand using the Imperius Curse or some other method of bewitching people to enhance his influence over them? Or do people really find him that persuasive? And how did he know what to tell Queenie?