Gallagher made his full debut in the 1-0 away win at Everton last week but was only on the pitch for a minute, while Hudson-Odoi was left out entirely.
Tuchel would not guarantee that both players would remain at the club this summer, with interest from other clubs ramping up, but urged them to be patient.
“In general nobody is for sale,” Tuchel said. “But it depends on what the player wants, how bad the player wants it, what we think about who is ready to pay a certain amount of money and then maybe everybody is for sale.”
Asked specifically about Gallagher, a loan target for West Ham, Crystal Palace and Everton, Tuchel added: “It is a very tough fight for him because at the moment it seems we only have two places in central midfield. Given the amount of players we have for central midfield, it isn’t ideal, I agree.
“We have to do what’s best for the squad, not just each individual player. But at the moment, he is absolutely fine and I am a huge fan of Conor. He is a fantastic guy. It is a very, very normal situation that after some fantastic training sessions in the beginning there is a little dip in his form and freshness.
“On top of that, there’s a huge competition. This is also life in a big club like Chelsea so everything is in its right place. We are happy with him. He keeps on fighting and this is what he does. I think he has everything to become very important at Chelsea.”
On Hudson-Odoi, Tuchel said: “Callum is the same. He had a long-term injury and problems to overcome. That’s where he suffered. I think he still has a way to go to live up to his potential. And his potential is huge.
“I think having Raheem in can give him an extra boost to step up and see what’s needed in these kinds of positions to reach the levels he can reach. But at the moment, he is our player and he needs to fight.”