The Path of Exile team has posted that the release date of the PlayStation 4 version of the game is being delayed. The team had originally targeted a December released, but the timeline has changed. PoE for PS4 will now be available in February 2019, though it's still possible it may arrive in January instead. Devs indicated that they underestimated the amount of time it would take "to finish the certification process during the busy Christmas period", hence the delay.
While we hope to have everything ready in January, we feel a lot more comfortable promising early February as a target release window. This will also give us time to work on game performance/frame rate, which we feel could be improved before release. Again, we're very sorry about this. We understand that many PlayStation users were keen to play Betrayal over Christmas and have been eagerly awaiting release date news. We promise that Path of Exile will be awesome on PlayStation 4 when it is released early next year.
Source: Path of Exile site