If Eckhart knew that Dent is dead (who knows better than the guy who played the character himself, eh?), then why did he say this:
"
Aaron Eckhart would reprise his role from
The Dark Knight - because working with
Christian Bale is "phenomenal".
Eckhart, who plays District Attorney Harvey Dent in the sequel, confesses he "absolutely" would star in a third Batman film.
He tells WENN, "To work with Christian (Bale) all over again, and the cast, would be phenomenal. I think this movie is a movie of a lifetime."
http://www.imdb.com/news/ni0265713/
Source: WENN.com
If Dent was officially DEAD, he wouldn't be saying this, unless the article above is completely false.
I'm not saying he is alive, but I'm not saying he is dead too. 50/50 for me. Just like WB (Emma Thomas) has said.