The PSP and Vita sold just 800,000 units in the quarter to the end of September, that's up a little on 600K the previous quarter. If you want to be positive, you can add 150,000 thanks to the Vita 2000 launch in Japan and Killzone in the west to kick start the new quarter. Vita TV and God Eater, and Tearaway in the west, will easily double or triple that, and the Vita/PS4 harmony should drive things further. Sony expects to sell 5 million this year, leaving 3.6 million to go over six months, not sure if that includes the TV unit.
All that activity is still small beans compared to the success of the PSP driven by GTA, Gran Turismo and Monster Hunter. Just one of those titles appearing on Vita might change the game, but Sony seems happy to sell it slowly but surely for the next few years. The success of Sony's smartphone biz might make portable redundant soon enough if the new wave of controllers takes off.