The question looms large because of China and Russia, two countries that could never be described as democratic, rule of law, societies. But both are large and threatening societies that are supporting thriving commerce. They make the issue cogent.
The towering example of Singapore, a rich, commercial, free market, thumbs its nose at democracy theorists because it is a one man autocracy which has been run by Lee Quan Yew for forty years. Singapore is an example of commerce thriving in a non-democratic environment
It may be possible for commerce to thrive in any environment, like Singapore, where the market is free, but the politics isn't, if the government remains stable over very long periods. We don't yet know the long term stability of Singapore. We do know that nepotism, the current Singapore model is doomed to failure, as all historic examples of nepotism show.
When Singapore fails, if it does, commercial interests may never again believe it is possible to thrive without democracy and rule of law.
On the other hand, China has succeeded in having a stable hand-off of
power once so far, while maintaining and expanding the fairly free
market and controlling the very commercial Hong Kong.
Time will tell if China can hand-off power repeatedly and whether a China that is stable over long periods will be an example of commerce without democracy.
The other issue that is of interest to me, requires thinking and maybe some new experimental nations as examples: Can a democracy survive without commerce?
There aren't many examples to look back on. Athenian democracy failed. So did the Seneca Indian model. I can't think of any others.
Historic examples don't answer the question. All the Viking countries and settlements were essentially democratic for a thousand years but the Vikings were an intensely commercial people. In most cases the Viking countries took on the appearance of a Royal Family but remained democracies, as they are today.
Most of the countries the Vikings settled, as the overlords, France, Russia and a few others, remained non-democratic for centuries.
Then there are the two unique cases of Switzerland and Holland. Both became democracies on their own. However, both were growing commercially before they were democracies.
What we have as historical examples are commercial societies that became democracies. We have no good examples of the opposite, a democracy that wasn't a commercial society.
My theoretical speculation as to the reason this is true is that democracy is an unstable form of government because in a democracy powerful people gain control and remain in control suppressing change and thwarting the democratic notion of decentralized decision making and decentralized power. Democracies, without commerce to destabilize them, without the new meritocratic leaders thrown up by commerce, devolve into long term stable autocracies.
Back to my thesis. Commerce is required for democracy. The reverse may not be true if the non-democratic government can have the rule of law and long term stability.