Did a bit of Googling and Nintendo is definitely not producing one. It sucks because it would have been nice to have a complete collection of guides for the Advance titles (FF I & II, IV, V, VI). Hopefully Brady will release one. Really odd though, VI is more anticipated than IV and V combined yet no guide. From GS forums:
http://www.gamespot.com/gba/rpg/finalfantasyviadvance/show_msgs.php?topic_id=m-1-33127193&pid=930370
http://www.gamespot.com/gba/rpg/finalfantasyviadvance/show_msgs.php?topic_id=m-1-33127193&pid=930370
I emailed Nintendo asking if they would be producing a strategy guide for FFVI Advance. Here is their response:
"While I can appreciate your interest in obtaining a Player's Guide for Final Fantasy VI Advance, Nintendo has not produced a guide book for this particular title. Our company is limited to the number of Player's Guides that we can release each year, therefore, we only produce guides for the most challenging games that are anticipated to be in high demand. For additional information on additional sources of game play assistance, please visit the Game Play Help section of our website."