If the document is genuine, the Samsung Galaxy S4 and the Samsung Galaxy Note 3 will be updated to Android 4.4 in January 2014. The Galaxy S III and the GALAXY Note III will each be updated sometime in the March-April 2014 time frame. Carrier branded models will take longer since each operator will need to test the update for each device. Android 4.4 will make each model smoother and more responsive with Project Svelte, the successor to Jelly Bean's Project Butter.
As usual, with such a high-profile rumor, we suggest you cast a cynical eye on the story.
Leaked document shows alleged time frame when to expect Android 4.4 update for certain Samsung models
source: iTechAddict via GSMArena