Is potty training considered operant training?

It depends on how the training is done. It could be done using operant conditioning. Most people do it that way. Operant conditioning just means that there are consequences for the dog's actions. When he toilets in the right place he is rewarded to encourage him to toilet in the right place more often in the future. When he toilets in the wrong place he is either corrected or interrupted to decrease the likelihood he will toilet inappropriately in the future.