Yes, rape, Guy Gardener
What do you think would've happened if she'd initially said no to Dukat's men? Do you think they would've just left her and her family alone to live out their lives in peace? I seriously doubt it! If she agreed to the sexual relationship with Dukat because her life and/or wellbeing or that of her family was threatened... that was rape. It's totally irrelevant that she developed feelings for him. If you don't understand why, look up Stockholm Syndrome.
And, yes, of course one can rape a whore.