It turns out that NVIDIA indeed had an Einstein project, but this was nothing more than a research project, and not something intended for release. NVIDIA revealed at GTC that Einstein morphed into Volta, which is the basis of all of NVIDIA's current GPUs, including the Turing series.
Rather than just being a baseless rumor, Einstein was in fact a real project at NVIDIA. However rather than being an architecture, per-se, it was a research GPU that the NVIDIA research group was working on. And although this research project didn’t bear fruit under the Einstein name, it did under another name that is far more well-known: Volta.