The G-Mode Archives release, like the original, will only support Japanese text (as confirmed on the Steam page), but it's possible an English translation patch will be available after launch. While the original game has been lost, a full playthrough video was uploaded to the Japanese video-sharing website NicoNico back in 2011, and has been translated into English by reddit user /u/penthesileaPicaro. Several of the G-Mode Archives releases have already received translation patches as well, including a spin-off of the original Persona, Megami Ibunroku Persona: Ikuu no Tou Hen.
No release date has been announced for the port, but it's possible it will be timed to coincide with the release of the Persona 3 Reload epilogue Episode Aigis in September, as both games focus on Aigis.