The German coach has been tasked with ending the national team's 60-year wait for a major trophy at next summer's tournament in North America and believes that team's performances in recent international breaks have shown that they have what it takes to go all the way.
Tuchel told BBC Sport: "We've got closer, we've got better. For my belief, I needed the camps in September, October, November, and the way the camps, the results and the group went together.
"Since then, our belief – mine and the group together – grew, and we will arrive to make a special thing happen. We cannot guarantee it but we will arrive with the biggest goal."
There has already been plenty of speculation about Tuchel's potential World Cup squad and the manager revealed that he has a clear idea of who he wants to take to the United States, Canada and Mexico.
The coach said: "I'm not sure if I know the starting XI but I know players I'm certain I want to have with us in the US. I know also there's some players who are very likely to start but let's take it step by step.
"It's my job to get to know the players, have a picture, an opinion, and then pick them and stick with them because they did so well to earn my trust. I have a clear idea."
Tuchel also revealed that he may get his substitutes next summer to remain in the dressing room during games because of the intense heat that is expected at matches.
He said: "If this is what helps us later in matches when they come on, we have to consider it a possibility.
"Nobody likes it because I want the players to be out there to feel the energy and give us energy from the bench on the field.
"But I saw players doing this at the Club World Cup. Hopefully we can avoid it. It's always better when they can be with us outside."