u/sapere_avde talks about PTSD in the Roman army here. There might be differences between the traumata incurred by gladiators and those by regular soldiers, but it is nonetheless worth a read.

Whether there is evidence or not it did happen. PTSD meaning post traumatic stress disorder is caused by a person perceiving an event as traumatic. There were obviously many traumatic events in the Roman Gladiator matches so it is microscopically impossible that there was never a person with PTSD. To look at recordings of this would be difficult because not much attention was put on slaves in their off time and if was recorded was most likely reported as insubordination. Not to mention the fact that to my knowledge Romans had no idea what PTSD is.