After four years of waiting, the animation director Takeshi Honda stated officially in an interview with the UK Anime Network that the fourth and final Rebuild of Evangelion movie is now in progress. Specifically he said:

"We're actually working on the new Evangelion film right now. We're working hard and it'll come out eventually, so thanks for all of your patience - please continue to be patient, because it's going to be the last episode."

Moreover, he expressed his hope that Evangelion will end properly before he retires, because drawing is getting physically more difficult as he gets older.

The first three films of the tetralogy were released in 2007, 2009 and 2012 respectively. The first film was entitled Evangelion: 1.0 You Are [Not] Alone, the second Evangelion: 2.0 You Can [Not] Advance and the third one was Evangelion: 3.0 You Can (Not) Redo. The title of the fourth film was announced in 2012 and is Evangelion Shin Gekijōban: || or else Evangelion: 3.0 + 1.0. The "||" at the end of the Japanese title is the symbol used in music to indicate repetition after the end of a measure.

Source: animenewsnetwork.com