The validity of e-Visa would be according to the e-Visa service you have requested in the application form as -
For e-Tourist Visa (01 year / 05 years), the validity would be 365 days / 05 years from the date of grant of ETA with Multiple entries and continuous stay during each visit which shall not exceed 90 days except nationals of USA, UK, Canada and Japan. In case of nationals of USA, UK, Canada and Japan, continuous stay during each visit shall not exceed 180 days.
For e-Tourist Visa (30 days), the validity would be 30 days from the date of your first arrival in India. Double entries will be granted within the e-Visa validity period stamped on your Passport. Your first arrival must be between the date of issue and expiry of ETA.
For updated list please visit https://indianvisaonline.gov.in/evisa/