Will be lost.

If the minimum level to repair is repair_allow_data_loss, it means that there will be data loss if that is run. There's only two cases that I know of (incorrect PFS pages and orphaned LOB pages) where repair allow_data_loss is required but data won't be lost.

In this case, there is a single damaged page in the clustered index. Repair will drop that page and fix the links. Hence, any data on that page will be lost.

http://sqlinthewild.co.za/index.php/2009/06/03/does-repair_allow_data_loss-cause-data-loss/