Ah, but ND didn't say that. DF did a tech analysis and concluded as so.
http://www.eurogamer.net/articles/digitalfoundry-the-last-of-us-tech-analysis
The extensive use of ambient and dynamic light sources is something we'd expect from a PlayStation 4 game, but Naughty Dog manages to pull it off well on current-gen hardware with only a few side effects: poorly filtered shadows cast by the sun can be unsightly up close, revealing that PCF and cascade transitions are still being used for performance reasons, while only characters appear to cast accurate indirect shadows. But despite this, the way both environments and characters are illuminated is used to great effect throughout the game.
In many respects, in fact, this isn't just a hint at what might be possible on a next-generation platform, but a game that delivers on that promise today, and we can't wait to see what else Naughty Dog does to surprise us in the future.