In Powershell you can use Get-Content with the -Wait flag:
Get-Content filename.log -Wait
You can shorten Get-Content to gc. That question suggested as a possible duplicate has an answer which mentions this and some useful extra parameters –
see https://stackoverflow.com/a/188126. I’m not sure if it’s really a duplicate, though, since that question is talking about general Windows alternatives to Linux tail, rather than about tail -f.