I agree with this claim. If it had not been for the French, the colonists would have had a very difficult time wining the Revolution and would likely have lost.
The American Revolution only ended with the Battle of Yorktown. It ended at that point because this was a major defeat of an entire British army and it seemed to indicate that the war could not be won. Of course, Yorktown would not have been possible without French aid. The French were instrumental in the Yorktown victory because they provided land troops to augment the American forces and because their naval forces blocked the British from evacuating Cornwallis's army.
Without this sort of help, and without the diplomatic pressure placed on the British by French recognition of the colonies, the British would have had a much easier time in suppressing the rebellion. We cannot know for sure, but it seems very likely that the Revolution would have failed without French help.