Christmas eve traditionally isn't too bad. Like it's not a weekday in February quiet, but it's around half of what you'll get a few days later.
The rest of this post is for people who google Gold Coast theme park crowds Christmas 2022:
For anyone wanting to know, barring abnormal weather, this year the busiest days at the parks will be the Tues the 27th and Wed 28th, probably the 28th will be the busiest this year. If I had to pick any park to visit, it would be WnW, arriving in the early/mid afternoon. Enjoy the wave pool, Calypso Beach, Aqua Racer, maybe Mammoth, and leave the rest till late after 4 till 7:30 close. The three weeks after boxing day are the busiest of the year, normally it does get a bit less hectic the further away from boxing day you get.
Weekends are often relatively quiet as people all as a group think 'I'm not going at the weekend during the holidays, it'll be too busy'. Understand I said 'relatively', it is still the peak season of the busiest year for a decade. It'll be packed. If you can delay your visit till something like the 19th of Jan, I would encourage you to do so. You'll hopefully get something more in line with a normal weekend, but will all coasters running all the trains available, extra shows to soak up the crowds and the same extended trading from the peak.
Good luck out there!