How long will Apple support the 5th gen iPad?

Define "support".

Obtaining service for your Apple product after an expired warranty - Apple Support

Typically you can receive software updates for about 7 years from new issue. There is no fixed rule but that's the way Apple has done things for a long time. I have an iPhone 8, we're on iPhone 16 models now, so that makes my iPhone about 8 model years old. It can run up to iOS 16 and when iOS 18 came out at the end of last year Apple no longer issued updates for iOS 16. Apple has in the past issued security updates for fairly old models but that is unusual and those are security updates, not general system updates. Once a model can no longer update, you'll find that app support drops off and after you're a few iOS versions out of date that you'll find that not many app updates are available. So likely in a month or two I'll find that not many new app versions will be available for my device. I can continue to use it as-is but maybe in a year or two I'll find that some services may no longer work, such as my connecting to my bank accounts. I will have to buy a newer device.

I know you have an iPad but the story is the same.

If this is a 5th generation regular iPad, support for major iOS updates has already stopped. That iPad can run iPadOS 16, but not iPadOS 17 or 18 or the iPadOS 26 that Apple will release this fall.

Which iPad type are you referring to exactly?

click here ➜ Identify your iPad model - Apple Support

There's the regular iPad, the iPad mini, iPad Air, and iPad Pro models which all have 5th generations.

The 5th Generation iPad released in 2017, is already unsupported for major iPadOS version updates. It received a security update in March of this year for iPadOS 16. iPadOS 16.7.11. It is unlikely it will receive any further security updates at this point.

iPad mini 5th generation is still supported with iOS 18, and will be getting iPadOS 26 this. It may be its last major update but should still receive security updates for a couple more years after that.

iPad Air 5th Generation and iPad Pro 5th Generation (11" and 12.9") Are compatible with the current iPadOs 18, will receive iPadOS 26 and should still get major iPadOS updates for several more years.