Yes, without fuel, ISIS will start to lose power. ISIS depends on oil revenue to fund the terrorists organization. Taking the oil revenue away will reduce their ability to fight and hold ground in the Middle East. ISIS will begin to lose much of its power after funding starts to run out.
Without fuel, ISIS will lose power. Of course, we need to determine what we mean by fuel. How does any terrorist organization fuel their campaigns? Fear. They require fear in the public and among the elected officials to create opposition. Without that opposition, people would not be drawn to their cause. Humans work with opposition all the time. We love to argue, to fight, to stand against something. ISIS requires that people hate and blame Muslims, so that Muslims will join their cause. What would happen if this didn't happen? If condemnation and hate ceased against the general Muslim population due to ISIS and other terrorist organizations? Those organizations would lose the very fuel they need to fund, arm, and carry out their operations.
ISIS does not create anything to fund themselves. It's not like they have natural resources or they sell shirts for a profit, and use the profit to fund their war efforts. Yes, without fuel, ISIS will start to lose power because they will not have the money or resources to advance their agenda.
Yes, without fuel ISIS will start to lose power because fuel is the only thing that is keeping them alive and profitable right now. They need fuel to make money. Without money, they will have no way of getting the weapons they need to fight. We must cut off their fuel.