Yes, QucsStudio is closed but it is improving, with the sole work of one maintainer. He asked for some support, without much success. Also, although it is closed, check the improvements of QucsStudio over Qucs and see if he only cloned the project and said it is his or if he really care about a better simulator.
Also to be clear, Qucs helped me a lot when I was searching free and open source simulator, and even showed me the world of open source, but the latest release is from 2017. QucsStudio still improving, and improving. Site, docs, tutorials, etc.
As both are good projects, and one is the foundation of the other, I think both deserve some credit and support.