It was more than Trump’s rhetorical question (200? 300?!) but I doubt it was as big as Trump’s crowd.
Here is the crowd size on O’Rourke’s Twitter:
Here is a crowd of 6,000 from something else.
http://bw-2e2c4bf7ceaa4712a72dd5ee136dc9a8-bwcore.s3.amazonaws.com/articles/Near-record%20crowd.jpg
I think your liberal friend is probably banking on the fact that the police department apppear to have not released a number, so nobody knows (but them, maybe).
Thank you, BlackAdderess.