The exact number of troops in each unit is unfortunately unknown. Together the armies of brandenburg and sweden numbered about 18 000 men.

You can see which units were from finland on the picture in the tread I posted a link to. They were positioned out on the left flank. (Finowie Berendsa= fins under command of Berend and Dragonia Finowie= dragoons from finland)

One note: this version of the order of battle (see link) comes from brandenburg. According to the swedish version the swedish infantry were grouped together with the germans in the centre.