What Movie Is The Quote, 'They're Dead! They're Dead! They're All Dead!' From?

The film you're looking for might be Mission: Impossible, which was released in 2006.
Mission: Impossible is an American action spy movie starring Tom Cruise as Ethan Hunt, an agent falsely under suspicion of murdering his entire IMF (the fictional Impossible Mission Force) team.

The line I'm thinking of in this movie is "Jim's dead! He's dead! They're all dead!". However, this might not be the film you're looking for, as similar lines of dialogue occur so often in film and television that proclaiming that everyone is dead has become a bit of a cliché. As a result, this type of dramatic line is often heard nowadays in shows like Family Guy which parody aspects of pop culture.

If you ever find yourself wondering about the origin of a different quote, searching for it on Google within quotation marks "like this" can often help you find the film you're looking for. This also works for song lyrics and book quotes, among many other things.

Hey I KNOW!! It's the first Mission Impossible movie, Tom Cruise said it.

I don't remember the name of the movie but the scene was on an airplane. Somebody from the past or future was creating a portal to impending tragedies and taking the live people and replacing them with bodies before the tragedy. The pilot said that line to the tower when he saw the replaced passengers before the crash

Have you ever watched "Highlander" or Blakes 7?  There are lines in the movie, Highlander, that are exactly like the ones you've asked about. 

I can't help but wonder if it was Invasion of the Body Snatchers.

These are the lines from Highlander.  Waiting for it to be aired soon . Going through your post reminded me of this movie and now I feel like watching it again. Let's see when do they air it on HBO

Tom cruise - mission impossible.