Can porcelain veneers wear away from eating?

A quick answer would be, No, veneers should not wear down from normal function.  However, bite plays a crucial role in treatment planning and design of a veneer case as the bite will determine the health of adjacent and opposite contacting teeth and life span of the veneers in regards to veneer debonding and fractures.

Compared to other cosmetic treatments, porcelain veneers are durable and long-lasting. However, veneers are not indestructible and may not last forever. Individual differences such as your diet, habits, and bite will affect the durability of the veneers and may eventually need to be replaced. 

Hi:Normally porcelain does not wear down. Porcelain against natural teeth wears down the natural teeth.  However, if there is any grinding pressure on the porcelain veneers it can chip or crack.Best,Dr. Maddahi