Explanation
This is a standard MATCH formula where the lookup values come from column H, the array is the headers in Table1, and match type is zero, to force an exact match.
The only trick to the formula is the use of a structured reference to return a range for the table headers to the MATCH function:
Table1[#Headers]
The nice thing about this reference is that it will automatically adjust to any changes in the table. Even when columns are added or removed, the reference will continue to return the correct range.