Yes, I wouldn’t be at all surprised if republicans strengthen their control. I think overall they are pretty happy that Trump has done a lot of what he says he would do, has waved the flag and ridiculed the evil football players, and they don’t give a damn about all this abstract Russia stuff. Plus he kicked out all those bad immigrants that are taken are jobs.
They definitely won’t strengthen their control. They may maintain a slight majority in the House, which would be a huge victory for them, but that isn’t strengthening their control.