Depends on the source. Some consider certain murders unrelated and opinions differ on when the war started. There have been dozens of people killed since 2004. The Montreal underworld became unstable after Vito's arrest, but the actual war started in my opinion with the murder of Domenico Macri in 2006. Around 30 directly related killings would probably be a good estimate, but total murders since Vito's arrest is probably 50+ by now.

There have been several phases. I'd say 2006-2009 was the prelude. Then the actual take-over attempt in 2009-2010 followed by a civil war within the anti-Rizzuto coalition in 2011-2012. Then the counter offensive by the Rizzuto group in 2012-2013 followed by relative peace until last year. You could make a case that these were several conflicts but all in all there has been turmoil and instability for over a decade.