Do you recommend a cold air

in take on a gas fireplace similiar to that on a slow combustion stove ?
Do gas fireplaces even have this option ?

I don't know if I totally understand your question but, this fall when I was looking into gas inserts alot of the new models have a compleatly sealed fire box and use a double lined flue pipe where the inner pipe is for exhaust and outer pipe is for incoming combustion air. This helps eliminate cold down drafts and heated room air going up the chimney. Lots of people suggest if you have a tight house outside combustion air is the way to go, but then again others disagree.

Alot of units today are Direct vent meaning they take air from outside for combustion like todd was explaining. There are several models that have primary air controls that can be adjusted. These are set to factory spec by the installer and should not be messed with. So really no they don't have a primary air control like an airtight wood stove does, you just don't have and or need that level of interaction with a gas fire. The consistency of the fuel and constant delivery rate make those controls unnecesary