I think that the American Revolution really did show the world that it was possible for a small group of people who held strong beliefs to topple a Monarchy and turn their country into something great. I think that did influence the French to try to make their country better.
While the American Revolution was being fought, at least one Frenchman, Lafayette, came here to help General Washington and others. Even though of noble birth, he had the egalitarian spirit, and when there was an uprising of his own people later, he took a leadership role there. We were definitely an inspiration to the French.
It's no question that the American Revolution inspired people in France to start their own revolution. However, it's a bit of an overstatement to say that the American Revolution was the driving cause. At best, all the American Revolution did was give the French the framework with which they could start their own revolution. However, it didn't drive the French Revolution. What drove it was the oppression of the lower class by the noble class and the vast income inequality between rich and poor.
While I do believe that it was a contributing factor, I do not believe it was the main driving force. During the time period of the French revolution the government was treating the citizens very poorly, which I believe is the main reason. If you are hardly getting the food required to live, you are likely going to revolt.
No, the American Revolution did not really provide the driving cause behind the French Revolution, because the ideas behind the two revolutions were similar. If anything, the writings of many French writers, and European writers, like deToqueville and Locke, provided the inspirations that the Americans needed to launch their revolution.