。
His success is due more to hard work than to genius.
Literal
His success [topic-は] genius [more-よりも] effort [to-に] attributable.
天才よりも努力に ('to effort more than to genius') uses よりも for explicit comparison. 帰する (きする, 'to be attributed to, to result in') is a formal verb from classical Chinese. The sentence makes a philosophical observation about the nature of success — effort over talent — with a formal, essay-like tone.