Yes, income from a sublease is rental income, generally reportable on Schedule E. The IRS says to report it on Schedule C "when you provide substantial services in conjunction with the property or the rental is part of a trade or business as a real estate dealer."
https://www.irs.gov/publications/p527#en_US_2018_publink1000219119
You'll also find the IRS definition of "substantial services" in that IRS reference.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
