If you want to display only entries created by users with a certain role, you can do that with Advanced Filters. Note: This functionality requires GravityView 2.0.14; filtering by role may not work properly in earlier versions.
Filtering by user role
When editing a View, scroll to View Settings and click "Filter & Sort"
Click the plus symbol button next to "Add a condition"
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 an 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 as well as an Administrator, then entries will be shown from all Editors and Administrators.
Note: "is not" filters are coming soon!
We at GravityView have submitted a patch to Gravity Forms to enable using "is not" when filtering by user role, and will release an update to add this functionality to Advanced Filters once it's available in Gravity Forms.