For what it's worth, the FAQ on his blog dances around this topic: "Running Shor’s algorithm to break the RSA cryptosystem would require several thousand logic

For what it's worth, the FAQ on his blog dances around this topic: "Running Shor’s algorithm to break the RSA cryptosystem would require several thousand logical qubits. With known error-correction methods, that could easily translate into millions of physical qubits, and those probably of a higher quality than any that exist today."