Hello,

See your year gap isn't going to act as a barrier when it comes to meet the eligibility criteria for UPSC as candidate needs to pass graduation in any discipline from a recognized university, those in the final year too are eligible to apply, when it comes to age candidates need to attain 21 years as on 1st August of the appearing year, so you can definitely appear for UPSC after graduation or as I mentioned you can apply in the final year provisionally provided you can show the proof of passing the qualifying examination within the prescribed time by the officials.