AFAIK there is no option for full "leather" seats on ZE50. The Zoe Microsite says the seats areI seem to have ordered a GT Line with textile seats. The heated seats (or Winter Pack)are standard on the leatherette trim, yes.
"GT Line part synthetic leather/part recycled fabric seat upholstery"
"Iconic 100% recycled fabric seat upholstery"
The site also stills shows the winter pack still as an option, so I would recommend anyone buying now gets in writing that included. I see it as a must have option for a BEV.