"どうすると彼女(彼)はクビになりますか?"
- How can she (he) be fired?
- What did they do to get fired?
何かをするとクビになるケース
- How did they get fired?
- How did she/he get fired?
- What did they do to get fired?
- What was the reason why (they got fired)?
(クビになった)理由は何?
What are some reasons why someone would get fired?
ご質問ありがとうございます。
別の言い方ですが、クビになったら理由を聞きたい場合、英語で「What's the reason for her(him) being fired?」と言えます。
もし、誰かクビになったではなく、一般的な質問の場合、「What are some reasons why someone would get fired?」と言えます。
ご参考になれば幸いです。