My brother just found out he has COPD does he need to stop smoking?

Yes, and yes yes. Stopping smoking is the surest way to slow the progression of the disease and increase both quality of life and the number of years that your brother may live. There are many methods to quit smoking - the most successful include medications plus a cessation intervention that focuses on behavior and social support. Your local physician should have information on both.
YES!!! COPD is a disease characterized by progressive airway obstruction. If a patient with this continues to smoke, it leads to continued airway inflammation and the disease progresses faster. If the patient quits smoking, the airways do not return to normal but the rate of progression is slower. In addition, the symptoms of COPD (shortness of breath, cough, wheezing, etc.) are also less. No cure exists.
Absolutely. Lung damage from smoking is the cause. Stop now!
Absolutely. Smoking will continue to cause his lungs to deteriorate. Needs to stop!