。
Studying will ultimately lead you to success.
Literal
Study-do [by means of-ことによって] eventually [topic-は] succeed (polite)-よ.
~によって ('by means of, by way of') attaches to a nominalized verb with こと to mark an instrument or means. 結局は ('in the end, ultimately') is the adverbial form of 結局. The よ closes with reassuring assertion — 'I'm telling you, it'll work out.'