Who gained momentum on last night's Raw (January 29th)?

Gained momentum: Elias

In his biggest win to date, Elias defeated "Woken" Matt Hardy and claimed his ticket to enter the Elimination Chamber. Though he probably won't win there, the Chamber will be a new dimension in his feud with John Cena. I'm hoping that the Undertaker rumours are wrong and that it will ultimately be Cena vs Elias at WrestleMania.

He probably won't win that match, but sharing the WrestleMania stage with a star of Cena's calibre would be huge for Elias.

As for "Woken" Matt? His feud with Bray Wyatt will continue, likely all the way to a WrestleMania match, so it's not too big a loss for him.