Are there any ways to save Gunnar guys? Despite his personality but I wanna save him from the death
[Spoiler]
No, either inform Everette the truth or help Scar, Gunnar still die. But helping Scar will make Gunnar love you. But he still die. ;w;
The fact that you can earn a heart just before he "dies" leads me to believe that he might not actually be dead. Give it some time and we'll see how the shapeshifter storyline continues to unfold.
I hope for his return someday too.