Why was France considered and treated as a “Victor Power” in the Second World War (more specifically, looking at how Germany was being divided and how France got to get pieces of it), realizing that they surrendered relatively early and, as such, didn’t have nearly as much impact as the other powers

Three main reasons: De Gaulle, the UK and the soviet union.

As the leader of the Résistance, a title that took him time, mens and energy to get, De Gaulle acted as the representative for Free France, with a gouvernement similar to the Résistance, rallying from the far right to the communists. De Gaulle had "une certaine vision pour la France" (a picture of what France should strive to be), and in this vision, it was an independant France, not shackled to allies, but leading with the front pack. This, of course, implied to overcome this position of "those who surrendered to Germany". To get there, De Gaulle argued that he had fought since day 1 against Germany, despite the surrender, insisting to increase the french military prestige, by an important involvement following the débarquement in Provence and the fighting in Germany, and, most importantly, by positionning France as the balancing power of western Europe, a theme that would become a cornerstone of french foregin diplomacy during the early days of the 5^th République (slightly out of topic, but still relevant, even today).

De Gaulle argued to the american Ambassador, that "the war over, the english will go back to their Isles, the americans to their side of the Atlantic: France will be alone on the continent, in front of Russia, and will have to strike a deal with her.". Similarly, he insisted for an alliance with Russia saying, in 1944, that "the key point of [a franco-russian alliance] is to deal with the german problem. Neither England, nor the US wants a Germany that has been too weakened.". This attitude led to De Gaulle going to Moscow in december 1944 and signing a declaration of friendship with the Soviet Union.

While the efforts deployed by De Gaulle to enhance french prestige and bring it back to the table of the Great Nations are impressive, they apparently didn't produce much results: France was present neither to Yalta, nor to Potsdam. Even worse, this focus on foreign affair led to trouble in the Levant, Algeria (with massacres the 8^th of May in Sétif, Guelma and Kherrata) and even Corsica, leading to the american asking his right hand man, Mendès-France, "How is he supposed to control the Ruhr, when he cannot maintain order in Corsica?". It took the effort of both Churchill and the soviets to allow France to gain its seat among the victors.

Churchill, despite his tempestuous relations with De Gaulle, sided with the french for multiple reasons: first and foremost, he was acutely aware that the UK, at the exit of the war would be a terribly weakened UK, that would greatly struggle to maintain a presence in continental Europe. On this regard, a friendly but weakened France appeared as a great tool to maintain some influence. Furthermore, most of the upper echelon of french Resistance's politicians had deep ties with the UK thanks to the war and a certain anglophillia, a pre-war legacy, reinforced by the UK attitude towards Free France. By allowing France to "regain its position", the UK bet on having a strong, friendly nation in the continent, able to stand against Russia as more than a roadbump and be a support as fellow colonial power. The bet would pay off, with France being very friendly with the UK durinig the 4^th République.

Why did the soviet, then, accepted to help France in its demands?

There is, first, the argument posed by De Gaulle himself: a strong France would be a neutral partner with the soviet Union. With hostility building up between the anglo-saxon and the russians, the need for the SU to have another "player" among the allies started to rise. Then, there was also the strong influence communists, the "parti des 75 000 fusillés" (party of the 75 000 executed, a false legend with a hint of truth). They were a part of the Résistance suprem council, and had the strongest french inner army at their disposal. While they had called for sabotage at the onset of the war, with Thorèz, the secretary of the PCF, fleeing to Russia to avoid his arrest in 1939, it was now the strongest branch of the french Résistance, incredibly popular (they would become the biggest party following the first free election) and with a strong influence on politics. France appeared, for Stalin, as a very juicy fruit. While convinced that a takeover by weapons was impossible, he encouraged them for a takeover through (legitimate) ballots. Even if it failed, they would have sufficient influence in the politics to guarantee a good natured neutrality towards the Soviet Union. In this regard, a strong France, not infeodated to the americans suited his plan perfectly, hence the actions of the soviets to favour a stronger France at the exit of the war.

Thus, despite the hostility of the americans, hostility that would quickly fade with the death of Roosvelt and the increase of tension with the soviets, thanks to good diplomacy, the figure of De Gaulle and the intersection of british and sovietics interests, France was able to claim the title of "Great Victors" of WW2 and a seat at the security council of the UN.