Samsung Germany used its Facebook page to announce that the Galaxy S Advance will be receiving Android 4.1.2 Jelly Bean in January.
The Galaxy S Advance was scheduled for an update in November, but Samsung decided to skip Ice Cream Sandwich for Galaxy S Advance and jump directly to Jelly Bean. According to the post, the Android 4.1.2 Jelly Bean update will be available via OTA as well as Samsung's Kies software. Samsung has been quite decent in delivering updates to older smartphones, unlike some other manufacturers.
In addition to the Galaxy S Advance, Samsung recently released a full and a rather impressive list of devices that will eventually be upgraded to Jelly Bean.
You can check out more here.