It's kind of funny NVIDIA, a dying company, is now saying this.
The reality is, PCs were always faster than consoles, by a lot. It's not physics, or power, it's simply that a console has to sell at a certain price point, whereas PCs, being modular can be quite inexpensive to quite expensive.
Also, SOFTWARE is the key to efficiency. You can't make the hardware more efficient for consoles, that's very true. But, the bloat in Windows slows things down dramatically, making consoles much more efficient in that area. That's a huge difference.
Windows is a very poor gaming platform, especially with Direct X. It's a business operating system, that they shoe-horn gaming into, but Windows NT was never designed for that, and still is not. If it were, it would be a lot smaller and faster.
Luckily, AMD just announced Mantle, but even so, you're still working with the bloated and flatulent Windows 7/8 OS, which is quite poor for gaming. Contrast that with an OS designed the other way - with games as the primary design goal, and by the way, we can also run other apps.
SteamOS and Mantle both illustrate the inherent inefficiency of Windows and Direct X as a gaming platform. They only exist for that reason. But, in the former case, it could very well bring the PC to an entirely new performance level that makes NVIDIA's crying more rational, and in the latter case, it will at least make Windows somewhat more competent at gaming.
Either way, with the consoles all AMD, it's hard to see NVIDIA as anything but a dying company as AMD leverages their wins there to garner greater optimizations in the PC market.
With Mantle now out, and GCN based APUs becoming more common as time goes on, the writing is on the wall, and it's saying NVIDIA is being terminated as a GPU maker, at least for games. They both have the same access to manufacturing, and their designs are always relatively close, so software optimization and ease of porting is an advantage that will put NVIDIA at a big disadvantage. They're done. They have no where to turn, no way out. AMD is finally doing everything right, and without a real CPU (they have toys like Tegra, but nothing real), NVIDIA had no chance to remain a viable GPU maker; AMD won the console wars because they could make an APU whereas NVIDIA could not. They leveraged that, now they are leveraging their win in consoles to terminate NVIDIA in the PC space.
It's about time to see AMD really innovate and leverage their advantages successfully. The black cloud that was known as Hector Ruiz is finally moving away, and the damage that incompetent jackass did is finally being recovered from. It's like a completely different company, and it's nice to see them back pushing new ideas and technologies, not just making inferior x86 CPUs at a lower price (while claiming an IMC is a real new idea, despite being done 10 years earlier in x86 by NexGen, or moving to 64-bits in a very straightforward way is really an innovation as opposed to an straight-forward implementation.).