53 Seats?

Nate Silver's forecast is within spitting distance of Sabato's:

 The model’s best guess is that the new Congress will be composed of 203 Democrats and 232 Republicans: a net gain of 53 seats for the G.O.P.

In addition, Democratic odds of retaining the House dropped to 17 percent from 20 percent; their chances of doing so essentially boil down to there being systemic errors in the polling and the other indicators that the model uses, as it is likely too late for them to alter the fundamentals of the electoral landscape.