From experience. Gar and crappie will spawn in same area. Gar spawn a little later than crappie.
What we have seen happen is if the gar come up early for their pre-spawn into those areas where crappie are, the crappie will hold tight to cover. So if you start to see lots of gar. Start fishing cover and fish so tight to it you start losing jigs.
This year the gar are very early. From buffalo to brushy gar have been thick as of week before last.
And yes the cats do line up with the gar when you see the gar doing their whale surfacing routine. Here in a week or so blocker bridge will have tons of large gar and the cats will be be on under them.