It is mentioned on many websites that he won many Olympic gold medals in cycling. In the film Khazanchi (1941) it is said that he was a "world champion cyclist". It is very easy to check these days. For example, this medal tally of India (sports-wise) shows that India has never won any Olympic medal of any kind in any kind of cycling!
Perhaps he won in the Commonwealth games. They have a website and one can search by athlete. I searched by entering Janki Dass, Janki, Janki Das. Under the last one, we find that he did participate in 4 cycling events in 1938, but was not even ranked in 3 of them and was 14 in the 1 Km time trial.
So, he went to the Berlin games in 1938. I guess it was a big deal just to be able to go, but no MEDALS.
So, was he ever a world champion cyclist? I have searched everywhere, but could not find anything. But, I know that absence of evidence is not the same as evidence of absence, I love to be proved wrong and I do reward handsomely those who find my mistakes. Please help me.
Now you know!