The only way to help someone with performance anxiety is to encourage that person to seek help. There is no other way around this, as the work needs to be done by the person afflicted with this. Once a person with performance anxiety seeks help, then there are various treatments that are effective, such as cognitive behavioral therapy (CBT) and prescription medication treatment with beta blockers.
You can also look into alternative treatments, such as CBT-guided self-help as seen in Anxiety Protocol, and anxiety natural supplements such as KalmPro:
