Can epilepsy cause a coma?

Yes. Some type of epilepsy cause come, coma means absence of meaningful response to external stimuli like sound, pain etc.
Complex issue. Patients with serious brain injury may have epileptic seizures and coma. Seizures may still be occurring even during coma. Eeg monitoring would identify on-going seizures. After severe injury the patient may have seizures that need intense medications that induce coma. Post seizures (post ictal) coma may be intense but fully recover. Usual epileptic seizures do not cause coma.