Although there are a number of ways to express "it depends" in Chinese, the most common ones in spoken Chinese involve the verb 看 (kàn). Some common expressions include:
Both 得看 (děi kàn) and 要看 (yào kàn) mean "depends on." Literally, they both mean "have to look at," so the logic is not hard to understand. Both of them are informal spoken patterns. If you're looking for more formal language, consider 取决于 (qǔjué yú), "to be dependent on."
If you're answering a question with "it depends on..." then this is the pattern you want. It's a bit simpler than 取决于 (qǔjué yú).
这 / 那 + 要看 / 得看 + [Unclear Situation]
Keep in mind that the "answers" below are meant to be an answer to some imaginary question that we don't include.
If you're going to write a full sentence explaining what "it" depends on, then you're going to need to lead off with some kind of explanation of the "unknown outcome" of what "it depends" on. So you'll start with the "unknown outcome" in the first part of the sentence (before 要看 / 得看), and then end up with what "it depends on" (after 要看 / 得看).
[Unknown Outcome] + 要看 / 得看 + [Unclear Situation]
The "unknown outcome" normally includes some kind of question word, meaning something like "whether or not x happens" or "what x does," etc.