The idea being floated is that the tax will incentivize innovation that leads to gains.

Taxes do not cause economic gains, but they can provide incentives that result in gains.  The open question (which truthfully nobody can answer with anything more than just a guess) is how much innovation will be triggered and how much of an economic gain that innovation will result in.

In any case, innovation takes time so we won't have an answer for a while, and it will only be after the fact that we know the true answer.