Though Subscene shut down new uploads, its archive is still accessible. It holds some of the best-preserved Ghilli translations from 2008-2015. Look for version tagged "DVDrip" or "BDRip."
The official Tamil movie channel Rajshri Tamil or Sun TV has occasionally uploaded Ghilli. However, the availability of English subtitles on YouTube varies. Sometimes they are hard-coded (burned into the video), sometimes they are auto-generated (unreliable), and sometimes they are absent. Always check the "CC" (Closed Caption) button before watching. Ghilli 2004 English Subtitles
Sites like Subscene, OpenSubtitles, or YIFY Subtitles host user-uploaded .srt files for Ghilli. If you have a digital copy of the film (DVD rip or personal backup), you can download these. Though Subscene shut down new uploads, its archive