Is this an orange or potiron birkin?

Looks like Potiron to me but one photo isn't enough to be sure....check the color reference threads esp if you have the bag in your possession. Basically H orange looks like the brand signature color and Potiron is accurate to its name.
 
Has potiron been discontinued?

I agree that it looks like Potiron, but it's very hard to tell from that one photo. Potiron is currently "rested" which in Hermes terms means it is not currently being produced.

So not "discontinued" per se, but you would not be able to purchase it from the boutique at this time and there is no guarantee it will be available in the future.