Killzone : Shadowfall (PS4)* - 1.45 ( number is as of January 22,2014, best selling next-gen exclusive) *includes bundles
So compared with titles they don't know the numbers for (I doubt SCE has access to Live's digital sales numbers) its the best selling next gen exclusive. That's not exactly revealing. 1.45 seems a decent number for KZ tho. KZ never exactly lit up the charts.
I'm not saying DR3 or Forza has sold more, but I doubt this source has proof of that.
<edit> I guess Capcom has announced (Link) 1m for DR3 (reached on Dec20).