If you are a contributor that seems to be invested in the project itself and not just your own issues/bugs/requests then you can probably join as a maintainer.
Although I'd probably ask, "Why do you want to be a maintainer"? (not to push anyone away). It's a question I (should) ask myself periodically. What kinds of things do maintainers do? I talk about this somewhat in my two talks: https://github.com/hzoo/maintaining-an-oss-project, github.com/hzoo/so-how-does-babel-even-work. It's not the most glorious thing, a lot of the work may seem tedious, github issues and dealing with people can be draining, and you end up not really writing that much code but doing a lot of project management.
For me personally though, it is worth it and fulfilling. It's an opportunity to learn JavaScript, getting involved in a programming community, learn many aspects of software engineering, and to serve others.