Can I update iPad 8th generation to ios16.1.2?

iOS 16.1.2 has been released for iPhone only. iPadOS 16.1.1 for iPad is current.

These models of iPad are all capable of update to the current version, iPadOS 16.1.1

• iPad Pro (all models)
• iPad Air (3rd generation and later)
• iPad (5th generation and later)
• iPad mini (5th generation and later)

As shown in the article linked above, yes.