>DIR /S C:SVN
...
     Total Files Listed:
           87268 File(s) 23,080,818,153 bytes
           15836 Dir(s)  216,886,992,896 bytes free

>(Get-ChildItem -File -Recurse -Force -Path 'C:SVN' |
    Measure-Object -Sum -Property Length) |
    Select-Object -Property Count,Sum

Count         Sum
-----         ---
87305 23081499113