Closing a contract without receiving any money is about the worst thing you can do for your Upwork reputation. Upwork algorithm considers that a fail. Try to spread out your existing clients' work and then get out of one of the contracts politely as soon as you can. If you really can't handle all of the work and have to cancel, just know that there may be a negative impact on your JSS score.
To answer your question, though: If you receive no payment, the client's star rating will not appear on your profile.
Tonya had already given you a nice and appropriate reply. But I was just amazed to see your post! There are a huge number of Freelancers are fighting for getting jobs from a few months! And you are the one who is a new freelancer here and you are not able to take the workload and you are thinking to tell the client that you can't be working for him because of your over workload? Don't you think this might impact badly on the client? Don't you think the client might lose his faith on the freelancers of this platform? A professional never should accept or commit to any project if he/she doesn't have time to do that project within the expected deadline or he/she is unable to do that. A professional never does this and this is a professional platform! You should better learn to manage the load or you should politely ask time to the client though you should do it before accepting the project.