Linked is the USyd magazine article published by their Student’s Representative Council.
The article says ‘over 500 students’, although other sources such as Green Left estimate over 700, with even News Corp publications (The Australian, Sky News, etc.) claiming almost 800 students.
One part which isn’t mentioned in those articles: Witnesses at the meeting told me there was some attempt to finish up the meeting before the second motion could be declared, which was counted with a chorus of “Let us stay!”. Apparently the meeting was only scheduled for an hour and delayed by a filibuster from a S4P speaker.