I think the source meant that the weight of the hull delivered is 50 tons. And the stupid jurno wrote it down as the weight of the tank.
But thank god Ambani is involved in Arjun now. We might get to see some decent numbers inducted in Army (~500?). Maybe, just maybe, Arjun MkII will now have a shot at the FRCV tender? I mean, they have a lot of time to improve on the design, and maybe bring the weight down to below 60 tons (which is the weight limit specified in the FRCV tender).
Hope Ambani also gets contracted for FMBT. If these guys become defence contractors, Indian indigenous industry might see another sunrise.