Is Upkeep +X cumulative?

[Aylin]

OK but for essence drain does it make a new upkeep on the creature or does it only work on creatures with upkeep already

It works on both creatures that have and do not have Upkeep already.

[baronzaltor]

"Upkeep +X" is a trait that stacks just like any other "+X" trait, no different than Melee +X or Bloodthirsty +X.

Multiple sources of Upkeep +X stack to form the total sum, which is the amount of mana you must pay during the upkeep phase or destroy the permanent.

Creatures with no upkeep can still gain the Upkeep +X trait, or it adds to the existing Upkeep Trait if there is already one present.

[sIKE]

"Upkeep +X" is a trait that stacks just like any other "+X" trait, no different than Melee +X or Bloodthirsty +X.

Multiple sources of Upkeep +X stack to form the total sum, which is the amount of mana you must pay during the upkeep phase or destroy the permanent.

Creatures with no upkeep can still gain the Upkeep +X trait, or it adds to the existing Upkeep Trait if there is already one present.

They do stack in the context as described. But are processed individually. So say you have an Invisible Stalker and a Dancing Sword. Your Upkeep is (+1)+(+1)=+2 Upkeep total. However what if you only had one mana left? You could choose to keep one or the other or neither. This is just an example, you get to channel before paying upkeep and unless you are running a large swarm and Mordok's Obelisk is out you should have the 2 mana available  to pay for both, but I am using it to clarify the answer, which I hope I have.