What happened to the Itachi Uchiha movie? As far as I know, a movie based on Itachi Uchiha was about to come in March.
Can anyone please tell whether it's coming this year or is it delayed?

Here is a Reddit thread of the poster, and here is a YouTube video of the trailer:

https://www.youtube.com/watch?v=Wl89gnvXcTg
This is not a movie. The Itachi Shinden novels are being adapted to a TV release, which will air this spring. I didn't see information about it beginning in March. 

The Naruto twitter account shared a link to TV Tokyo Naruto website which has a small trailer and information about the release, which seems to indicate that it will begin airing in Japan on April 7th.