Pumpkins which are part of the gourd family are heavily associated with thanksgiving celebrations and Halloween.
The reason being is that on thanksgiving it is tradition to have pumpkin pie and during Halloween people like to crave pumpkins to make jack-o-lanterns.
So can gerbils eat pumpkins at all?
Yes, but in strict moderation which means just a very small piece and not often.
The reason being is that pumpkins contain a lot of acidic content and also a large amount of phosphorus content which is not good for a gerbils health.
Therefore if you were to give one or two small pieces just big enough for them to hold in their hands that should be more than enough as a treat once in a blue moon.