Covid 19 – Event Restrictions

At the current time different states have different restrictions around Covid 19 and events 

Northern Territory Events of less than 500 people can occur with distancing and without approval from the chief health officerEvents of of more than 500 people can occur if approval is given by the chief health officer https://coronavirus.nt.gov.au/roadmap-new-normal/business/guidelines-for-events-and-gatherings

South Australia The density requirement of 1 person per 4 square metres still applies for Defined public activities but any given room or enclosed area cannot have more than 75 people present. Where a place has multiple rooms or enclosed areas, the maximum number of people at that place cannot exceed 300 people. These requirements apply only to patrons, not staff.

So, a single-room restaurant can only have 75 customers, plus staff. A facility with multiple rooms and outdoor areas can have up to 300 patrons, provided none of those rooms exceeds the 1 person per 4 square metres rule, to a maximum of 75 people per room. Also, if two Defined public activities take place at adjacent places, (dining in clubrooms and playing sport on an adjacent oval) up to 300 people could be dining, and another 300 could be playing or watching sport on the oval.

Tasmania Gatherings are restricted to 80 people (excluding staff) and the four square metre rule per person applies.

New South Wales
Currently 20 people but from July 1 “The number of people allowed inside indoor venues will be determined by the one person per 4 square metre rule, with no upper limit. This includes function centres. All activity must be seated only.” so a room that could hold 300 can now have up to 80 people. 
Victoria Currently 10 people

Western Australia Activities listed below are allowed for up to 100 people per single undivided space, up to 300 people in total per venue over multiple spaces (100/300 rule), while ensuring physical distancing, good hygiene and the 2 square metre rule are followed:

Public gatherings

• non-work indoor and outdoor gatherings of up to 100 people per single undivided space, up to 300 people in total per venue over multiple spaces (100/300 rule)
• weddings and funerals up to 100 people.

Canberra Public gatherings have a limit  one person per 4 square metres for indoor or outdoor spaces, up to 100 people.

Queensland After July 10 up to 100 people