As of now, the game has been announced to feature only English audio and voice work at launch. Japanese audio will be looked into as a DLC option, but Hardin offers no guarantees.
It’s important to note all Western releases of the Persona titles have only included English audio. Over the years, a number of JRPG fans have preferred to play with original voice work only – the reason being that some feel that Japanese voice acting is superior in terms of the retaining the game’s original intent. The same fans feel that localized voicework with script changes is a form of censorship.
Fans can be rested assured that ATLUS has recognized the request and will see if it can be included.