It does effect damage buff but i am not certain about pets though, anyway next patch they will hit hard so doesn't matter really xDGReaper said:It will certainly not increase damage from earth pets. They're stuck at the level of the elemental which you cast, whatever damage they do varies on their level only.
As for damage add, it possibly acts like cleric buffs where getting 44 earth with spec, items and realm rank would give you the full amount of the buff. However I'm unsure on it myself and only some tests would give you the answer.
Still, not worth it whatsoever.