Gyokeres has taken Henry's old No14 shirt as he arrives from Sporting CP as Arsenal's senior centre-forward.
Henry said: "He already was in England, let's not forget that. He was at Coventry, he couldn't do it at Brighton.
"So, you can see a guy who already knows what struggling is and comes back from that.
"He's more confident, and you can see from his body the way he's looked after himself, the way he's changed.
"You have a guy that's a killer in the box – numbers don't lie – and you have a team that creates a lot of chances, so it should be the perfect match.
"It's always unfair when I talk about a striker, it brings an unnecessary pressure because it goes above and beyond.
"What you want is people to be patient with him, and what is annoying right now is that people are not that patient anymore.
"They want the guy to perform straight away, score goals straight away and make us win straight away, which doesn't happen often. Sometimes it doesn't click straight away.
"I love when people show me what they can do, and then I can talk. Right now, people love to talk before the performance.
"I'm an Arsenal fan, I obviously hope he's going to do well, bang goals for us, and guide us to a title, but he's not going to do that alone.
"We have seen that goals don't always assure you a title. We've seen guys with mad numbers, but they didn't win anything. The team around them has to be good.
"From what I've seen from him and how he finishes, hopefully it's going to be a great match and we can finally go back to lift that trophy. But, a lot of teams want to lift that."