Is it safe to take beta blockers for pvcs if alsi have asthma?

Maybe not. B-blockers result in bronchconstriction, meaning the airways tend to close whereas b-agonists tend to bronchodilate, or open the airways. So, b-blockers may result in airway closure leading to acute asthma symptoms. (note: even b-blocker eye drops can have this effect!) some b-blockers do this to a lesser extent than others so check with your doctor first.
Depends. The severity of your asthma & the severity of your arrhythmia dictate which course to take. There are some beta blockers that don't impact the breathing tubes much. Discuss this with your doctor before you use the beta blocker.