Excel is not right tool for this job
According to Excel specifications and limits, worksheets are limited to 1 048 576 rows. You can have as many worksheets as your computer can handle before it exhausts memory.
But I'm not sure if that format (one file split into eight sheets) would be suitable for any useful analysis.
This file must be loaded into few worksheets. The best approach would be splitting it into eight slices (there are few tools available if you search the web for "split text file Windows" - I have never used any of them) and then load them sequentially into Excel. VBA can you help in second part.