Windows Service in C# to load very large flat file to MSSQL Table

General information for the business: We sell holidays
Kind of development: New program from scratch
Num. of modules: 1
Description of requirements/functionality: A large file is provided daily as a compressed gz
This needs to be uncompressed, and the contents uploaded to an MSSQL table.
The extracted live file is very large, it is pipe delimited and about 3Gb in size, containing 3.5 million records. There are 202 columns.

I have attached a sample of the data and the schema for the table (please ignore the final few columns).
Specific technologies required: C#
OS requirements: Windows
Extra notes: THIS IS IMPORTANT

The performance of the upload is important - I need this to be fast.

also please answer the questions attached to the job or I will decline the proposal.