What is a "gap year"? Fundamentally, it's a rite of passage into adulthood, a chance to explore the world while considering "Who am I?" "What's important to me?" and "What do I want to do with my life?"
Getting into graduate school is not easy, but paying for it can be even more of a challenge. Because graduate school is so expensive, you should have some idea of what you hope to gain from the investment of time and money you're making.