Up to 70 million as of a day ago https://www.bloomberg.com/news/articles/2023-07-07/meta-s-threads-has-70-million-signups-surprising-zuckerberg

I'm not concerned how many of these are real users - all the shills, the bots, are even worse than real users as they will just be spewing their propaganda around as much as possible.

Adding ONE million users overnight to the fediverse would be disruptive enough, 10x the biggest day from the influx from reddit. We're looking at orders of magnitude more than that.