I always thought that he cared for Ziyal only because Kira cared for her. He wanted to impress her.
So you don't think he loved Ziyal, but you believe he loved Kira so deeply and passionately to risk losing his career, social standing in the Cardassian Union, his mother, his wife and his 7 Cardassian children?
And you really think that makes more sense than the idea that Dukat loved his daughter?
I thought Dukat after a while was a really stupid character who did really stupid things. Probably because he was insane and the people close to him like Damar liked to ignore that. So yeah that's right. He's going to kill his daughter but NO! Kira protests and he realizes if he wants some Bajoran booty he can't kill her. He takes care of her and becomes a model father to impress Kira.