As I know only literal string is required in the from. In that case you have to write a dynamic query to use bulk insert
declare @q nvarchar(MAX);
set @q=
'BULK INSERT [TStagingTable]
FROM '+char(39)+@CSVfile+char(39)+'
WITH
(
FIELDTERMINATOR = '','',
ROWTERMINATOR = ''\n'',
FIRSTROW = 1
)'
exec(@q)