While it might not be the first to an upgrade to Android 4.4, the Samsung Galaxy S4 gaining Android 4.4 KitKat will certainly be a significant contributor to increasing the number of Android users on the latest OS. Tomorrow Rogers' version will, according to the Rogers OS upgrade page, getting an upgrade to KitKat. Rogers' OS upgrade page has been pretty spot on in the past so we expect the upgrade to roll out as promised.
While we can't confirm it, Samsung has traditionally been able to synchronously roll out the updates to their devices and we expect the S4 to get the same treatment. If you have an S4 keep an eye out for the update tomorrow and let us know how it goes.