One thing you're forgetting about the Greek and Italian city-states is that they were part of an overall "culture" which allowed for spread of ideas among the larger culture.
What somebody in one of the Italian city-states thought up would have spread to other parts of Italy and to the rest of Europe.
IMO when you talk about the numbers needed for "a scientific, technological or social revolution", it isn't just a matter of the number of people in one state, but as we see with Europe, it can be a matter of how many outside of that state are involved in the discussions.
Europe had a "common language" in Latin and had an educated class willing and able to discuss ideas with little regard to "national" boundaries.
It has been argued that the lack of a common government aided in the spread of ideas in Europe as no group had the power to stop the spread of ideas.
The Safehold Church had the power to stop the spread of ideas.
Once the Safehold Church loses that power, the spread of ideas on Safehold will continue.
Thucydides wrote:Since the Gbaba are essentially McGuffinite to start the series, I suspect that RFC has not actually given them much thought beyond the few "nuggets" of information we already know. Until they reappear in book 97, there is no real need for us to know more than they are an existential threat lurking "out there".
As for how many people you need to start a scientific, technological or social revolution, consider the city states of Ancient Greece or Renaissance Italy. These polities had far smaller populations and resource bases than many of their competitors, yet made great advances in science and technology, and were able to use their resources far more efficiently than their much larger competitors.
The Greeks managed to defeat the much larger and more populous Persian Empire in the Persian Wars. In the Peloponnesian War, Athens was eventually stripped of most of her possessions and lost the flower of her fleet and Army in Sicily, yet continued to fight Sparta ad her Allies (who were backed with Persian money) for another 9 years.
Venice, a small city state, was competitive with the Ottoman Empire for almost 200 years, and really only started to decline when the Venician Senate chose to concentrate on building an empire on Terra Firma, consuming much needed resources to the detriment of the fleet and overseas trade.
On a slightly larger scale, the United Provinces of the Netherlands pretty much fought the Spanish Habsburgs to a standstill, and Elizabethan England did the same despite the Spanish having the largest population and a virtually unquenchable flow of silver from the new worlds to finance their wars.
In all cases, while the smaller polities usually could demonstrate some technological advances over their opposing Empires, the real key was rapidly evolving social changes and the ability to use resources far more efficiently than anyone else. (Greek mercenaries were in high demand in Persia for their heavy armour, but what made them effective was the organization of the Phalanx. Similarly, the Ottomans often used galley designs and cannons smuggled or made by Italian renegades, but the Venetian fleet had far more combat power because the rowers were free men armed and expected to fight when the ships came in contact. Their merchants were also much better trained and organized, so the Venetians were also richer per capita than the Ottomans).
Size does matter in the end (the Athenians and Venetians eventually ran out of manpower), but having a flexible and open social structure coupled to a continental landmass (like the United States) should provide an unbeatable combination. The EoC may be overtaken by the Republic of Siddarkmark at some time in the future by leveraging these factors.
