How does GravityView know who can edit the entry?
GravityView performs two checks before allowing a user to edit an entry on the front-end:
1. By the entry creator
By the entry creator: if the form was submitted while a user was logged in on the website, then the user ID of this currently logged-in user is stored as entry meta. GravityView will compare this ID stored as an entry meta against the ID of the currently logged-in user. If it matches, then the user can edit the entry.
2. By user capability
By a specific user capability: we have a knowledge base article specifically made for this: Allowing a user to edit all entries.