have you tried civil records ?
see :
Introduction to Irish RecordsAs jud72 mentioned his father's name and occupation would be useful to try to locate the correct family on the 1901 census and also help you confirm, or rule out, any possible birth certs or baptisms.
The townland of Gilltown is in the civil registration district of Naas and there are two possible birth matches (both recorded without a middle name) in the right district at around the right time - probably civil birth records for the same baptisms that jud72 mentioned :
Name: Thomas Doran
Registration district: Naas
Event type: Birth
Quarter and year: Apr-Jun 1883
Volume : 2 / Page : 852
Name: Thomas Doran
Registration district: Naas
Event type: Birth
Quarter and year: Jan-Mar 1884
Volume : 2 / Page: 831
A civil cert would generally give a bit more detail than a baptism .
Shane