From a theist standpoint, you've got the entire point of this question wrong.
That is, you're focusing on whether God has a need for a certain number of followers. In other words, you're confusing God for a figment or qualia. Qualia are subjective factors of the human mind, like how "red" the sky is at night. The idea also being that you can somehow make God more or less real, like a figment. A God is a free-standing agent, something which does not require food or water or attention yet still continues to exist. The idols of the ancient world were not a God, but rather dependent on human worship.
But this question is backwards because God doesn't need our worship. We need a relationship with God. You may ask, why do we need a relationship with God? Isn't God just an imaginary friend? That's what an atheist will tell you.
But in fact there is a marked difference during certain situations between an atheist and a theist. Let's call this "crisis mode." For example, your wife left you, you lost your job, and your supposed friends suddenly call you a failure. Setting aside both the efficacy of prayer and the question of whether God is real or not (I could tell you, but it's not relevant here), a believer during such crisis mode has two support systems that an atheist would not have: an extra group of people from church to talk to, and the ability to approach God in prayer. In other words, before we even get to the question of whether a believer is saved or not, they still have a noticeably better life in two major points, which aids in their ability to bounce back during a crisis.