Pure Transact SQL (sin utilizar una llamada SQL dinámica que no forma parte de TSQL):
SELECT
CASE WHEN c1 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c2 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c3 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c4 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c5 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c6 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c7 IS NULL THEN 0 ELSE 1 END
+ CASE WHEN c8 IS NULL THEN 0 ELSE 1 END
FROM T