Is it possible to get taxi from Temple of Heaven going to Tianjin Cruise Port and approximate cost.

The distance is about 105 mi (169 kilometers). If by taxi it would cost probably CNY600.

Here is another way for you:
take a taxi (with about CNY25) to BJ South Railway Station, where you can take the intercity high speed train to Tianjin Tanggu Station. From the station you can take a taxi (the fare would be around CNY70) to reach the port. The train costs CNY79.5 for first class seat, and CNY65.5 for second class seat.