There are several methods of doing this- for example, we think UNSW might based it off of ranks, an explanation is
here.
Your UMAT percentile would also matter more than your raw score, seeing as raw scores correlate to different percentiles each year, depending on how hard/easy the UMAT was that particular year. Using your UMAT percentile, which is out of 100, and your predicted ATAR, which is out of 99.95 (close enough), it is fairly easy for Curtin to then go (ATAR*0.60)+(UMAT*0.40) to figure out who to invite for interviews.
Unfortunately for us, we can't tell exactly what the cutoff is, but trawling through
this thread may give you an indication of what sort of scores will receive an invite. Please note that these scores will vary from year to year, and that they also depend on factors such as rurality, EAS, etc.
It all depends on how you compare against other applicants as to whether you get an interview as well. (Universities can only interview a set number of people).