My son has g6pd, can he eats tapioca?

Tapioca is ok. Haven't heard of any problems with eating tapioca, which is a starch made from the root of cassava, used for tapioca pearls, puddings, and as a thickening agent in foods.
G6PD.org - food info. G6pd deficiency makes red blood cells vulnerable to oxidative stress from some drugs and foods. Fava beans, legumes (like soy!) and blueberries are examples to avoid. The starchy plant tapioca should be fine. To find great info on g6pd deficiency, check out the website g6pd.Org.