The difference between the terms "Literature Survey" and "Literature Review" is covered in this question and answers. But how do they differ from "Research Gaps" in the context of a research proposal?
The difference between "Literature review" and "Literature survey" is small, if it exists at all - people may use the two terms to mean the same thing. It has been discussed in this question.
A "research gap" is an area of research that has not yet been done. You may identify a research gap by doing a literature review or survey.