Depends on how you define "Armenian genocide" and "ending".

One prominent view is that the genocide ended in late 1916 or early 1917. For example, R G Suny (''They Can Live in the Desert'' p. 330) states:

The Genocide of the Armenians can be said to have ended by late January

1917. Mass starvation continued, as well as sporadic killing. Refugees died, and fighting between Armenians, Turks, and Kurds went on until the early 1920s, but the intentional massacre of Armenians and Assyrians by the Ottoman state gradually ceased.

Here "Armenian genocide" is defined, more or less, as the systematic deportation of Armenians from Anatolia to Syria and Iraq and their killing in these destination areas. Later losses from Ottoman and Turkish invasion of the Caucasus in 1918 and 1920 are seen as a separate but related event.

Another end date is 1918 (for example Khatchig Mouradian), when World War I was ended by an armistice and the Ottoman Empire effectively collapsed, enabling some Armenian survivors to rebuild their lives. However, in most parts of what is now Turkey, Armenians were blocked from returning home.

Others end the genocide in 1923 (for example, this demographic study), when the Turkish state was established. They would include the invasions of the Caucasus and the ethnic cleansing of Armenians during the Turkish independence struggle as part of the genocide. However, the displacement of Armenians from other parts of Turkey beyond Istanbul continued after 1923—thousands of Armenians were deported from southern Anatolia to Syria in the 1920s. Another continuity is the kidnapping of young Armenian women, which did not end in 1923 either. (Talin Suciyan states that for decades afterwards, "Many Armenian girls were unable to attend local Turkish schools because of the danger of kidnapping" ''The Armenians in Modern Turkey'', p. 65) The legal barriers to establishing any kind of Armenian community in Turkey outside of Istanbul continue to the present day.

A fourth point of view is that in some ways the genocide never ended, manifesting in such forms as denial and erasure of cultural heritage. (Compare the Palestinian view that the Nakba is ongoing.) Suciyan's book discusses what she calls the "post-genocidal habitus of denial", but she explains:

Here, the ‘post’ in post-genocidal does not mean that genocide has come to an end; on the contrary, the catastrophe of genocide is endless and irreversible. However, it has to be acknowledged that the character of physical violence and the attendant policies deserve special consideration in the period of the ‘crystallisation’ of these policies. Therefore, ‘post’ stands for the period of crystallisation in which exclusive genocidal policies were implemented and the denial of the catastrophe, in abstracted and encapsulated form, turned into the habitus spanning the decades leading to the present. (21-22)

This disagreement on what the genocide is and when it ends is all about how you define these things.