Formal:
* Pouvez-vous taper en anglais? (Poo-vay voo ta-pay ahn ahn-glay?) This is the most direct and polite way to ask.
Informal:
* Tu peux taper en anglais? (Too peuh ta-pay ahn ahn-glay?) This is a more casual way to ask, suitable for friends or family.
* Est-ce que tu sais taper en anglais? (Ehs-kuh too say ta-pay ahn ahn-glay?) This literally means "Do you know how to type in English?", and is a slightly more roundabout way to ask.
Other options:
* Parlez-vous anglais? (Par-lay voo ahn-glay?) This means "Do you speak English?" and is a good way to start the conversation if you're unsure if the other person can type in English.
* Je voudrais vous demander de taper en anglais, s'il vous plaît. (Zhuh voo-dray voo de-man-day duh ta-pay ahn ahn-glay, see voo play.) This is a very polite and formal way to ask, suitable for professional situations.
The best option will depend on the situation and your relationship with the person you're asking.