This returns "Approved" if all eight are "Approved", otherwise "Rejected".
=IF(AND([Approver Status 1]="Approved",[Approver Status 2]="Approved",[Approver Status 3]="Approved",[Approver Status 4]="Approved",[Approver Status 5]="Approved",[Approver Status 6]="Approved",[Approver Status 7]="Approved",[Approver Status 8]="Approved"),"Approved","Rejected")
This is a bit better as it returns "Rejected" if any are rejected ("OR") or "Approved" if all are approved ("AND"), otherwise returns "Pending".
=IF(AND([Approver Status 1]="Approved",[Approver Status 2]="Approved",[Approver Status 3]="Approved",[Approver Status 4]="Approved",[Approver Status 5]="Approved",[Approver Status 6]="Approved",[Approver Status 7]="Approved",[Approver Status 8]="Approved"),"Approved",IF(OR([Approver Status 1]="Rejected",[Approver Status 2]="Rejected",[Approver Status 3]="Rejected",[Approver Status 4]="Rejected",[Approver Status 5]="Rejected",[Approver Status 6]="Rejected",[Approver Status 7]="Rejected",[Approver Status 8]="Rejected"),"Rejected","Pending")
Little better formatted version:
=IF( AND([Approver Status 1]="Approved", [Approver Status 2]="Approved", [Approver Status 3]="Approved", [Approver Status 4]="Approved", [Approver Status 5]="Approved", [Approver Status 6]="Approved", [Approver Status 7]="Approved", [Approver Status 8]="Approved"),"Approved", IF(OR([Approver Status 1]="Rejected", [Approver Status 2]="Rejected", [Approver Status 3]="Rejected", [Approver Status 4]="Rejected", [Approver Status 5]="Rejected", [Approver Status 6]="Rejected", [Approver Status 7]="Rejected", [Approver Status 8]="Rejected"),"Rejected", "Pending")