Let's start this out properly by saying this: there is no actual evidence to support this claim. There is only a collection of suggestions by anonymous sources for various blogs. That means the information could very well all be coming from one person talking to a number of places and giving the same wrong (or right) information, and we have no way of knowing...
Source: http://www.phonearena.com/news/Rumor-claims-Nexus-5-and-Android-4.4-KitKat-coming-October-14th_id47430
Source: http://www.phonearena.com/news/Rumor-claims-Nexus-5-and-Android-4.4-KitKat-coming-October-14th_id47430