According to Chinese Wiktionary, it originated in the period when mobile phones where large, expensive bricks and were carried as an accessory by triad bosses ("big brothers") in Hong Kong movies. https://zh.wiktionary.org/wiki/%E5%A4%A7%E5%93%A5%E5%A4%A7
大哥大 dates back to at least the Sino-Japanese war. It's northern slang equivalent in meaning and connotation to "da boss" (eg. the term is mostly used sarcastically). I've never heard anybody use it as a term for cellphones. So no, the term predates Orwell.