WOW!! I can't see that happening. That would mean holds in PA and OH with wins in NJ and MD. In addition to holding ALL the other close Senate seats (MT, MO, TN, VA and RI). I think a more realistic prediction is a net loss of 2 in the Senate (losses in PA, OH and either MT or MO with a pick-up of MD). The House is hard to tell I could see a slight gain there, but expect to lose a handful, keeping control.
I don't think we're talking about net gains here. I think he/she means: Republicans hold the House by 8; the Senate by 2.