There's stock audio files available which are used here. The laughter audio files have been long recorded & the same is used even in those Comedy nights with Kapil & other shows.
It's a common norm to do that. We have set of stock audio files which will be used as bgm in TV shows, films etc. They're all licenced ones.
Not saying every laughter is old recorded one. But most are because it's not possible to record live with the same desired effect. All the award shows (Indian with an exception of national awards), it is recorded audio files (laughter) only that dominate. Some laughter audio files are decades older.