[hnbad]

Well, the article says the "ganj" root in "Ganjifa" is Persian. I didn't know the etymology of the word "ganja" before so I had to look it up:

"Ganja" seems to originate in Vedic Sanskrit but its exact etymology seems to be unclear. It might be related to Sumerian "ganzigunnu" or it might be related to "Ganga", the Sanskrit name for the Ganges river. It might also share an origin with the word "cannabis" via Indo-Germanic.

In other words: it's unsurprising you wouldn't find related words in Hindi given that neither of the two words originates in Hindi, although Hindi is generally believed to be a modern descendent of Sanskrit (via Hindustani). The more relevant language to look at would be Farsi (i.e. Persian). With regard to Hindi they're two unrelated loanwords, one of which is even a proper noun.