In my humble opinion, just as "no taxation without representation" is a thing the gov should abide by; "no representation without taxation" is probably good too. If these company's want to vote, have them pay 50% of all the money they every make to taxes.
Actually, not even then. If they want to vote, even if they paid 99% of their profits towards taxes to vote it would be a bad idea.
You have no criticism from me on this. Companies either should have no say in politics at all, or a whole shit ton of actual, meaningful penalties for abuse if they do.
The government already doesn't abide by that principle. Votes cast by people in left-leaning areas count for a small fraction of what votes cast in right-leaning areas count for. Those convicted of a crime may not vote at all. Nor those without citizenship. Yet all of these groups pay taxes.
If taxation without representation were generally considered revolution-worthy, as it once was, there would have been a revolution decades ago.
I'd say tax them equivalent to all the individuals in the company combined. If there's a 1000 employees, charge them the same you'd take 1000 people all at once. Then maybe triple it to account for the fact that they amplify the efforts of those people many times over.