Due to the lack of official documents on the one hand and demonstrable certainty, the Belgian government usually set a date of death of victims between the time of deportation and the end of the Second World War. In the official Belgian Government Gazette, the dates of death were then listed as the transport date of the deportation. The place of death was not mentioned too, as the exact place was not known.
In such cases, the Jewish Monument mentions "Unknown" as the place of death, and as the date of death the officially used Belgian date of death, which is usually the date of transport and deportation to the extermination camps.
Even though the Jewish Monument says something else, you may assume with a very high degree of probability that Jacob Stokvisch arrived from Mechelen in Auschwitz on 26 September 1942, but his exact date of death is not known. It is also unknown whether he was employed in Auschwitz or elsewhere. Therefore, his exact date of death cannot be ascertained.
Source: The Memorial of the Deportation of the Belgian Jews, description Convoy VIII (8), page 24.