So my friend says,
"I guess it was inspired from Y movie #X movie"
I corrected him by making a small change to the sentence,
"I guess it is inspired by Y movie #Xmovie"
X movie is about to release. Am I correct ?
Okay, so you have two points here: the tense of your sentence (was or is) and the phrasing of "inspired from." As Arrowfar stated, "inspired by" is the correct phrase. When it comes to tense in this case, though, it's a little ambiguous. Referring to events in literature or film, I believe the rule is that you always speak in past tense, i.e. Frodo THREW the ring into Mount Doom, instead of Frodo is throwing the ring into Mount Doom. However, you're presumably talking about the creator of whatever work of art you're talking about, not the work of art itself. Having said that, it's safe to assume past tense here, since artists are inspired to create their piece before they even start working on it.
There are really three issues here:
As others have noted, the correct preposition to use after inspired is by, not from. I'm not sure that there is necessarily a logical reason; that's just how it is.
Unless you are talking about the very early stages of creating the movie, when the script is still being written, the inspiration is an event that happened in the past. That's true even if the movie has not been released yet. Therefore, you should use the past tense: was inspired by.
How to put the sentence together?
An example of a correct sentence would be:
I guess West Side Story was inspired by Romeo and Juliet.