Here are some relevant definitions:
in preposition
14 — used to indicate a job or area of activity
▪ She has a job in marketing.
- Learner’s Dictionary
on preposition
9 — used to indicate the subject of something
▪ a book on [=about] North American birds
- Learner’s Dictionary
“In” has the sense of “within the field of”, while “on” has the sense of “about” or “regarding” in the context of your quote.
Your quote has two possible antecedents to on: “thesis” and “degree”.
A thesis can be on a topic, meaning that it addresses that topic. So you can have, for example, a thesis on medicine - the thesis addresses aspects of medicine as a totality. You can also have a thesis in a topic or field, but that’s a looser tie between the thesis and the field. A thesis in medicine is one written about a medical topic, not necessarily about medicine as a whole.
Degrees are only awarded in fields of study, not on them. You can have a degree in (within the field of) medicine, but saying you have one on (about) medicine sounds odd.
The phrase “for receiving” also sounds a little off. It would be more natural to use the following wording:
- an «MA» degree was awarded for his thesis in Translation Studies on phrasing.