Can the iPad mini update from 9.4 to 13.3

Please go to Settings app, General, About and post your iPad's model number.

If your iPad Mini has been stuck on iOS 9.3.5/9.3.6, you may own a 2012, 1st generation iPad Mini, which cannot be upgraded any farther than iOS 9.3.5/9.3.6.

If that the case, on the iPad Mini, 2 the highest it can go is iOS 12.4.5. If you really need iOS 13.3.1, you need newer iPad Mini.

Yes it can. But somebody skipped iOS updates, you have to do it with iTunes on personal computer via USB.