Not directly, no, however it will definitely make breathing much harder and much more tiring. When you have pneumonia your lungs may get filled with liquids and so it will be much harder to breath. You will not necessarily suffocate 100%, but you can develop many bad conditions due to the lack of oxygen in your system. It is very dangerous to not treat pneumonia and when you feel that it is hard to breath it is a bag sign. It is always important to visit the doctor as soon as the couching does not go away. If you feel mucus in your chest also make sure you see a doctor as soon as you possibly can. So bottom line is: you will not suffocate 100%, but you will have trouble breathing and such trouble will evolve to other bad things that will definitely make you suffer.