That's nice, I live along Lake Shore where I can anecdotally tell you that they have been running buses to supplement streetcars at various points in the day and at night, so no it is not 100% streetcar. The number of bus runs vary everyday, sometimes there are 4 out at any given point, other times there are 7, next moment there are 9. It really depends on the day, time and section of the route.Anecdotally, I can tell you about 50% of the streetcars I see on Queen now are ALRV, which is down obviously from then it was 100%.
But no, they don't have buses running to supplement streetcars on the 501. My office literally looks out onto Queen West. I've seen none since they stopped running the 501L for Long Branch, when they were rebuilding the Humber loop and bridge. It's now 100% streetcar from Long Branch to Neville Park.
And no, 50% of the streetcars operated on the 501 are not ALRVs. At this point if there are ~20 ALRVs left, and more than 150 CLRVs left, just do the math.