Can a Pokémon caught before Gen 2 release evolve and get Gen 2 moves?

I have two Dratini and 145 candy, I want to evolve one of them into Dragonite.

#1 Dratini

• 484CP 94% IV
• Caught 08/02/17 (before Gen 2 release)
• Moves: Dragon Breath / Aqua Tail

#2 Dratini

• 474CP 88% IV
• Caught 27/02/17 (after Gen 2 release)
• Moves: Iron Tail / Aqua Tail

My question is, can a Pokémon that was caught before Gen 2 was released get the new moves available after Gen 2 came out or would it end up with Gen 1 moves?

Is it worth evolving #2 Dratini just incase?

Yes, this is noted on the Silph Road Gen 2 Release megathread:

Newly caught gen 1 pokemon can have new moves too, like Iron Tail on Dratini. Evolving an already owned gen 1 pokemon can also result in a new moveset, like getting a Dragon Rage/Outrage Gyarados from your old Magikarp.

To prove this, I started evolving my old Pokémon that had updated movesets until I got one with a Gen 2 move:

As you can see, I caught this Seaking as a Goldeen on 9/11/2016, long before the release of Gen 2, but it has Ice Beam, which was only just added to Seaking's move pool with the release of Gen 2.