Are non-computer science PhD students using ML/AI techniques expected to publish in top CS conferences like NIPS/ICML? I am a second-year Ph.D. student where my topic is focus in the domain of civil engineering. However, I am also utilizing several machine learning/artificial intelligence in my application to achieve my end goals. While I understand that publishing in top computer science conferences such as NIPS, ICML is definitely a plus to my resume and achievement, I'm wondering will it be out of my research focus? From what I understand those paper submitted there are focused on producing theoretical contribution in the computer science domain and it would take quite some time to produce such contribution and I feel like I will drift away from my research topic. I'm asking this as I'm sort of being forced to submit there (aka supervisor pressure).

Any suggestion?
Most conferences in any field are looking to present advances in that field. This is usually called novelty. If you are using standard techniques in AI/ML in your work then it may not be seen as very interesting to CS folk, unless the application is, itself, somehow, novel. The standard for that will be fairly high. 

So, ask yourself where is the novelty in your work and publish/present in journals/conferences in that field. 

But the bar for submission is low and it will be reviewers who make the judgement about suitability. So, if you want to do a trial submission, to see how your work is judged, you are free to do so, making your advisor happy. But, I agree that your general research trajectory is more important.