Can I get admission to a private college with 55% marks in 12th standard and a GUJCET rank of 33?

Yes, you can likely get into a private engineering college in Gujarat with 55% in your 12th standard and a GUJCET rank of 33. Many private colleges offer admissions based on a combination of 12th board marks and GUJCET rank, and a rank of 33 is generally considered a good score, so you don't need to worry.