The taxes hadn't gone up. When it goes up, they'll move money as they already do.
Population is irrelevant. They are not a grocery store; no retail operations. They have no reason to stay in France if taxes go up. They can conduct business in France without being in France.
You think Google can't "outsource"? Of course they can and will. They aren't going to stand by and watch a French tax smash and grab. They will make them an example so that other EU nations don't try and follow suit.