It all can be fixed with money, if you talk to one of the developers of coinmarketcap, and tell them that you want to list your coin (and it does not has a good volume, of course) It can still be listed if you pay them a pretty fee
I am talking about over one bitcoin / half one, of course.
But yes, if it has good volume and it is being a succesfull project, it can be easily listed in there, only that you will have to wait some days, maybe weeks until it gets listed in there.
And you must know that having a coin listed on coinmarketcap is a very good thing for all your investors, because they are always going to be looking at that webpage to see if your coin is real, or if it is a shitty one.