Clearly, this game is important for both teams. The Seahawks need this game just to get into the playoffs. The Niners need it to secure the second seed in the playoffs and get the first round bye.
However, I think the Seahawks have more pressure because:
1. Obviously they are in more survival mode right now since they still havent clinched a playoff spot yet.
2. The Niners already spent alot of their mental and emotional capital last week in New England. Since SF is already in the playoffs, this game won't feel as big as it should ( they SHOULD view it as a big game cuz it is. But I'm worried they wont. I guarantee you Niner fans are pumped up about this game)
3. Pete Carroll is desperate and under the microscope because he has been owned by Harbaugh for such a long time. If he keeps losing to Jim, people will start asking Pete questions like "what's your deal?" (in a very mocking, derogatory way that might get into his head).
4. For this specific game, I think most of the media is picking the Seahawks to win this based on home field advantage and based on the fact that the Seahawks blew out the Tards and the Bills. Usually, the favored team feels more pressure to perform. Just human nature.
Whether or not the increased pressure helps or hurts the Seahawks, I dont know. Some people perform at a higher level when under more pressure. Russell Wilson appears to have that quality in him, kinda like Montana. Kaepernick has been pretty impressive in big games as well but the sample size is too small to really know how good he is. Should be an exciting game.