It's laughable that this is your criteria - Trump hasn't murdered 6 million people - YET. The only difference at this point is that Trump is at the beginning of his dictatorship, and Hitler didn't start murdering people until he'd been dictator for 5 years.
Hitler seized power in 1933. The first concentration camp didn't open until 1938. So far, Trump is ahead of Hitler's timetable for an authoritarian takeover.
Everything Trump does is right out of the authoritarian playbook, starting with the demonization of "others". Trump's demonization of immigrants is EXACTLY the same that Hitler did with the Jews - blaming them for the Treaty of Versailles which impoverished Germany.
After Hitler was elected Chancellor, it took him 53 days to dismantled the democracy. Trump is ahead of that schedule, and Congress is rolling over, playing dead, and allowing him to do it.