If you want to display only entries created by users with a specific role, you can do that with the Advanced Filters extension.
Filtering by user role
Note: This functionality requires GravityView 2.0.14. Filtering by role may not work correctly in earlier versions.
When editing a View, scroll to the Settings Panel and click the "Filter & Sort" tab:
Click the "Add Condition" button
Then choose "Created By User Role" from the first dropdown
Choose the role you wish to display entries from
If you choose "Any Role of Current User", the currently logged-in user's roles will be used
All of the user's roles will be used to filter the entries: If a user is logged in and the user has the roles of "Subscriber" as well as "Customer", then the filter will show entries from users who are Subscribers OR Customers. If the current user is an Editor and an Administrator, then entries will be shown from all Editors and Administrators.
You can also use "is not"!
You can exclude entries created by users with specific roles by selecting the "is not" comparison from the filter dropdown.
To show all entries that were not created by site administrators, you could add this configuration: "Created By User Role" "is not" "Administrator", as shown below.