How Much Dmg Does A Lvl 26 Gigado

Hello there!
Me and some of my guild members were wondering about the following;
How much DPS should a Mage with the following gear, enchants, gems and spec do:
http://www.wowhead.com/profile=33998424#inventory
For privacy reasons I did not link to armory page itself, but copied everything to the wowhead profiler, hoping that'll do just as well (this Mage is not mine).
Currently he is doing 34k DPS on the Madness of Deathwing encounter (10m Normal mode) and we feel this is too low. His DPS became even worse when he specced into the Fire tree. Our other DPS-ers do anywhere between 46-52k. So my question to you is how much DPS should he do on the Madness of Deathwing encounter? Specifically, in the Fire and Arcane talent trees. If you only know about one or the other, that'll do as well.
More importantly, if our suspicions are right and his damage is way too low, how can he improve his spec/gems/enchants to do better? What should his rotation be (Arcane/Fire)?
Please help us out, because we feel he is holding us back progression-wise.
Thank you!

How Much Dmg Does A Lvl 26 Gigado 3

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