Body language in the interview is closely related to the job-hunter's image.
Surely it is.
You should look the interviewer in the eye so as to show that you are carefully listening to him.
You can nod or ask questions at the right time to show that you have already understood or you are quite interested in his words.
When you are seated, bent forward a little with your hands crossed, to show you respect the interviewer.
Don't move from time to time. It is very impolite and will make you nervous.
Proper posture can show your confidence.
The best would be you have a smile on your face in the interview to win a good impression of the interviewer.
Pay attention to keeping eye contact as well.
Throughout the interview you should maintain patience.
In a word, you should keep decent manners in the interview.
Only in this way can you leave the interviewer a good impression and achieve success.