This page of the guide to The Quarry explains whether you can save dead characters. You will learn how to enable this option and how it affects gameplay.
Once you're in the game settings, select the "accessibility" section. There, you will find an option that's enabled by default. However, if you want, you can turn it off, so that it does not affect your gameplay. The option in question is "death rewind". If one of your characters suddenly dies, this option allows you to reverse that, load a save and make a different choice. This option only works for deaths that happened due to the player's lack of attention, missing a QTE, or a bad decision before a crash.
What does death rewind look like? A special selection window appears on the screen after a character's suddent death. It takes away from the immersion, so if that's important to you, turn this option off in the game settings right away.
The window shows how many lives you have available in general. There are 3 lives in total that cover all characters. If you use one of the hearts, you can save the life of one protagonist. Using this option will take you back to a choice you made a moment before, so the one that directly determined the character's fate, such as a missed shot or choosing the wrong path.