1.1 use a browser to open the text file to detect the encoding being used. If using Chrome, you can find the encoding being used by clicking menu -> more tools -> encoding.
1.2 use the detected encoding to parse the text file and check the parsing result in the Clipboard is correct. (If Chinese characters are not displayed correctly, make sure your client machine's OS does support Chinese fonts.)
2.1 by manually executing an insert statement, insert a record that contains Chinese characters to the table where you observe question mark instead of Chinese character.
2.2 execute select statement to see if those Chinese characters got saved in the table correctly. If they didn't get saved, you need to contact your DBA.
If there is no problem to select and display Chinese character by executing select statement,
3.1 try to display the record inserted manually at above step 2.1 on the screen, using your pega application.
3.2 If Chinese characters don't display correctly on the screen, contact your application server administrator to check if the JDBC setting uses a Chinese character compatible encoding.