Yes. People in Bangkok and in other tourist destinations in Thailand can speak a basic but decent English. And that is valid for daily life (taxis, restaurants, bars...) and for business life, since most of the people working for companies with offices in Bangkok can speak some English.
You may find some trouble with communication in the countryside, where people are not so familiar with English.
In any case, a basic knowledge of Thai will be well perceived by the locals and will allow you to better experience your stay in Bangkok.