Please replace C:\work\ with your folder name where 1000 of *.xlsx located. Run below script in SSMS with you modification.
Script
-- Create temp table
create table #files (ID int IDENTITY, FileName varchar(100))
BULK
INSERT #files
FROM 'c:\test.csv'
WITH
(
FIELDTERMINATOR = ',',
ROWTERMINATOR = '\n'
)
select
'INSERT INTO TableName Select *, ''' + FileName + ''' as ''SurveyName''
FROM OPENROWSET(''Microsoft.ACE.OLEDB.12.0'',
''Excel 12.0;Database=C:\work\' + FileName + ';HDR=YES'', ''SELECT * FROM [Sheet1$]'')' as 'InsertSql'
from #files
-- Drop temp table
Drop table #files
Results will give you instert statement for each .xlsx file. Copy/paste these statements in to SSMS and execute(F5) to load the data.
INSERT INTO TableName Select *, 'Files1.xls' as 'SurveyName' FROM OPENROWSET('Microsoft.ACE.OLEDB.12.0', 'Excel 12.0;Database='C:\work\Files1.xls';HDR=YES', 'SELECT * FROM [Sheet1$]')
INSERT INTO TableName Select *, 'Files2.xls' as 'SurveyName' FROM OPENROWSET('Microsoft.ACE.OLEDB.12.0', 'Excel 12.0;Database='C:\work\Files2.xls';HDR=YES', 'SELECT * FROM [Sheet1$]')
Copy and paste