For users like me, who use kde as their daily de, Tixati always looked ugly due to the fact it uses gtk as gui library instead of qt: will qt ever be supported?

I don't think so. It might upgrade to gtk3 but I don't expect it to completely switch from gtk to qt.

From the comment in this ( https://forum.tixati.com/support/1982  ) discussion looks like it’s planned, but it’s from almost 5 years ago

Any news?

would using QT allow tixati to have the breeze dark theme added to it? Id love to be able to make tixati match the rest of my system in theme colors.

Yes, using qt Tixati will be rendered, via the current qt render engine, with the theme and color scheme you selected. In your case Breeze is both the engine and the theme, so Tixati would be rendered as the rest of the applications.
PS: note that exists a GTK Breeze theme that you can use right know to uniform GTK applications, like Tixati, to the rest of the system, but, due to the limitation of GTK (at least GTK 2, I don’t know if it is the same with GTK 3), the windows will be rendered always with the default breeze color scheme, so, if you have changed that, Tixati won’t still look uniform with the rest of the system.