How much would approximate taxi fare cost from Beijing Capital Airport to my hotel in Dongcheng?

If you take a taxi, the fare should be around CNY80 from the airport to your hotel.
Or you may take airport express to Dongzhimen, then transfer to subway line 2 to Yonghegong; leave from Exit F and go southwards along Yonghegong Street until you reach the western end of Beixin Hutong. Walk along Beixin Hutong to find your hotel.

Thank you. Most helpful.