The GPU max Memory available is some 32 GB in some high end devices.
A100 has 80GB, but as memory usage is not linear, it does not really matter. GPU is not a magical tool which would solve any problem any time. Especially when we talk about memory usage - in case of GPU you CANNOT use memory as a simple storage as it will affect your performance a lot. There is probably somewhere a golden rule, between the same algorithm on CPU and on GPU, but definitively it does not work like "just give me more RAM".