The literal translation is:
The role（役割） of the new character（新キャラ） is damage(DPS, Damage Dealer, whatever you want to call it).
The original text itself seems to be missing a few necessary words (but the meaning is conveyed, so I guess it's for Japanese speakers).
I think it would be easier to understand if that sentence was written as:
"新キャラの役目は、ダメージを出すという事を主としている - The role of the new character is primarily to deal damage."
As for 「になっている」 part.
The word "になっている" means that there is a rule, habit, or schedule/plan that dictates what you/someone/something will or will not do. So yes, I think it's safe to say that you're on the right track.
In this case, the word "になっている" was used because it is planned that a new character will be implemented with the role of dealing damage.