If you force me to give actual numbers, I'd say GOP+5 (AK, AR, LA, SD, WV) in the Senate and +8 for the GOP in the House. A +7 Democratic gain requires a Democratic victory in the popular vote of 1-3 points, which I don't see happening.
No it wouldnt. Essentially an even popular vote would probably give Democrats a seven seat gain. If Republicans do gain seats, it wont be more than five, as there are very few Democrats left in tough seats.
Why? Essentially an even popular vote should give essentially the same result as 2012, as the lines won't change and the vote was essentially even in 2012. Also, there are significantly more vulnerable Democrats than vulnerable Republicans:
Democrats who won by a margin of 5% or less in 2012:
1. Ann Kirkpatrick (Arizona 1)
2. Ron Barber (Arizona 2)
3. Kyrsten Sinema (Arizona 9)
4. Ami Bera (California 7)
5. Julia Brownley (California 26)
6. Raul Ruiz (California 36)
7. Scott Peters (California 52)
8. Elizabeth Esty (Connecticut 5)
9. Patrick Murphy (Florida 18)
10. Brad Schneider (Illinois 10)
11. John Tierney (Massachusetts 6)
12. Carol Shea-Porter (New Hampshire 1)
13. Tim Bishop (New York 1)
14. Sean Maloney (New York 18)
15. Bill Owens (New York 21)
16. Dan Maffei (New York 24)
17. Mike McIntyre (North Carolina 7)
18. Pete Gallego (Texas 23)
19. Jim Matheson (Utah 4)
Republicans who won by a margin of 5% or less in 2012:
1. Mike Coffman (Colorado 6)
2. Dan Webster (Florida 10)
3. Rodney Davis (Illinois 13)
4. Jackie Walorski (Indiana 2)
5. Andy Barr (Kentucky 6)
6. Dan Benishek (Michigan 1)
7. Michele Bachmann (Minnesota 6)
8. Lee Terry (Nebraska 2)
9. Tom Reed (New York 23)
10. Chris Collins (New York 27)
11. Jim Renacci (Ohio 16)
12. Keith Rothfus (Pennsylvania 12)
An analogous list would show there are more Romney-Democrat than Obama-Republican districts. The math suggests that, without a more Democratic climate than 2012 was, Democrats will probably be largely on the defensive in the House in 2014.