Jīngguò duōnián nǔlì, tā zhōngyú kàndào le chénggōng de shǔguāng.
After years of effort, he finally saw the dawn of success.
Tips
usage
曙光 is almost always metaphorical in modern Chinese - you'll hear 胜利的曙光 (dawn of victory), 希望的曙光 (glimmer of hope) far more than literal references to dawn light.