By definition, a pseudo-seizure is a "non-neurological" seizure type of episode. (gathering you are talking about Epilepsy, not drug reaction seizure)
Best evidence in either, neurological or non is video and having the person give a statement on paper RIGHT AFTER the "episode" for lack of a better term, based on your post.
Secondary is witness statements telling how the person acted, if there were any physical abnormalities, verbals, musculars, if the eyes could be seen. Time it took for "recovery" and so forth.
It may or may not be epilepsy, but if it resembles seizures, treat it as such until proven one way or the other.