That depends on a number of things. Theoretically the leverage is infinite, as companies can not get anything done without workers. However in practice, strike funds won't last forever, people won't be willing to strike forever, it's in your interest to keep a relatively good relationship with the company, etc.
Granted, it will vary person to person for a lot of good reasons, but it seems to me like the average white-collar tech worker out have a lot more personal savings than the average blue-collar factory worker.
