I don't have a primary source, but discussions on the Dragon Age wiki mention David Gaider himself admitting the ASOIAF inspiration. Of course it's not the only one. Dragon Age's elfs are inspired by the Witcher, its magic/Fade/demons by Warhammer 40k psykers/Warp (and yes, it's a ripoff, though Wh40k ripped off Dune and Moorcock, this particular take on daemon-possessing psykers etc is copied straight from it), references to LOTR are obvious, etc.
It always was a mash hup of whatever was popular among fantasy fans at the time. Only thing that was a bit original was Qunari (well the schtick of making a race of communist mage-hating folks wasn't totally new neither, but it wasn't as blatant as other references) and they did try to do something interesting with the setting in the Awakening DLC. Which is funny, cause they totally canned that storyline in latter games.
EDIT : found a source :
https://venturebeat.com/community/2...-interview-part-ii-creativity-and-the-novels/