Yes, you can.
Bulk Import Reviewees:
Navigation: Admin > 360 Feedback > Recent Cycles
1. Select a cycle from the list.
2. Click Manage Participants under Add Reviewees and select Import to import reviewees to the cycle.
3. Follow the instructions on the popup window and click Next to import the employees.
Bulk Import Reviewers:
Check out this article to learn about importing reviewers in bulk.