There doesn't seem to be anyway to report bugs regarding FFXV. So far the best you can do is Tweet or Facebook post but its likely that is not being monitored or responding. Even these Forums appear to be unmanaged, So if you have any Bugs I guess you can try these methods

1. Post here
2. Tweet @ FFXVEN
3. Post on FFXV Facebook
4. If the Bug or Glitch is Game breaking you can Contact Xbox Live or PlayStation Network and they will refund your purchase regardless of purchase date. This only applies to Downloaded versions of the game if you own a Disc you can try to return it at the retailer but its unlikely if you purchased it over 30 days ago

how you should Post a glitch or bug here: Example (this is a real bug)

Game : FFXV
Console: Xbox One
Digital or Disk: Digital
Bug Summary: Gil Missing
Bug Description: Gil completely disappears for no reason when loading save game. Chapter 3
Fix: No way to fix it
Date: May 25 (immediately following latest patch