Generally, interview from CS department will focus on the following topics:
0. Your Personality
1. English proficiency
2. Data structure, operating system(maybe including computer architechture)
3. Your domain knowledege. Eg, ML, DM, AI, CV.....Although this is the most relevant field you will work on in the future as a graduate student, however, most of the time, it is the last factor for an instructor to consider.