It's not even close to a 45B model. They trained 8 different fine-tunes on the same base model. This means the 8 models differ only by a couple of layers and share the rest of their layers.

Which also means you can fit the 8 models in a much smaller amount of memory than a 45B model. Latency will also be much smaller than a 45B model, since the next token is always only created by 2 of the 8 models (which 2 models are run is chosen by a different, even smaller/faster, model).