Yes, English is widely spoken in Istanbul although the official language is Turkish. You can get around with English in tourist areas, hotels, and restaurants that cater to international visitors. For added convenience, get the 2000 most common Turkish words book to increase your fluency while in Istanbul.   English is spoken and understood by many people in the tourism industry. There are signages in English and most menus would have English translations. However, proficiency in the English language decreases once you are outside the main tourist sites.