Is Alcatraz visible from Battery Spencer?

Yes

I am planning to go there. From the StreetView Image, it seems to me the island is visible, behind the Golden bridge.

Yes, great view of the city, the bay, and Alcatraz

You can "see" Alcatraz, on a clear day, no wind, afternoon sunlight, and binoculars or telescope.

Yes you can, as long as it's clear day.

It absolutely is! Just look to the left.

We can see it when there isn’t fog

I could be wrong but I didn't see Alcatraz from there