How many raisins can you eat? Is this ok? Can you eat a few more?
How many raisins do you want? Can you eat this many? Do you want (some) more?
レーズンは可算名詞なので、次のように言えます。
ーHow many raisins can you eat? Is this ok? Can you eat a few more?
「レーズンどれくらい食べれる？これでいい？もうちょっと食べれる？」
ーHow many raisins do you want? Can you eat this many? Do you want (some) more?
「レーズンどのくらい欲しい？これだけ食べられる？もっと？」
ご参考まで！
カナダ 
