From my side, there isn't really a strict “minimum CAT score” that GIBS publicly declares like some colleges do. When I applied, CAT was just one part of the whole selection and a lot also depended on the GD/PI, communication, clarity about why PGDM, and overall attitude.
I've seen classmates with very different score ranges getting selected because GIBS looks more at potential and how you present yourself rather than just the number. So even if your CAT score isn't too high, it doesn't close the door — they genuinely focus on the student, not just the percentile.