I have never personally cited an interview and am not too familiar with the Chicago style but I would recommend the following (refer to this link):
Note number. Name of person(s) interviewed (if this is not included in title of interview), "Title of Interview," interview by name of interviewer, Title of Journal, volume number, issue number (Date of publication): page number(s) listed for pdf files or under a descriptive heading if no page numbers, Persistent/stable URL or name of database if online.
(This is just one of the many different ways of citing an interview when it comes to Chicago style. Refer to the link above to see all the types that are possible and select the one that matches the source).
Please note that an interview that has already been published or broadcast is treated like articles in periodicals or chapters in books.
Now, when citing multiple interviews, you (or your friend) could introduce the reference the first time it comes up in full. Then, whenever it appears next, cite it in the shortened form. Consider using the Latin abbreviation "Ibid." when you refer to the same source twice or more in a row.
Have a look here to see how to use "Ibid." and on how to use shortened form. As mentioned before, the interview can be treated to be the same as a published article and hence using this link should not be a problem.
Hope the above was relevant.