It can be made easily with Envelope distortion if you accept a bit simpler arragement of the crosses and let them be distorted:
Draw the zero shape, make the hole by subtracting the mid part from an ellipse.
Prepare a chunk of crosses. Different sizes are easiest to make in the beginning with blending:
Split the zero to halves horizontally and vertically with lines (Object > Path > Divide objects below), tile crosses until you have enough to be bent inside the quarter of the zero by using Envelope Distortion:
Unfortunately the simplest way to apply envelope distortion (=Make with top object) creates a mess, Illustrator's automatic distortion mesh is totally wrong. A better way is to make the envelope distortion with mesh. A two rows x one column mesh applied to grouped crosses can be edited manually easily inside the quarter zero with the direct selection tool:
For best fitting be sure that the handles in the corners are strictly horizontal and vertical.
Make three flipped copies of the distorted crosses. The mirrored seams look bad, it's better to expand the envelopes and delete the nearest of the seam cross rows from top left quarter and bottom right quarter. Moving the quarters against each other fills the gaps. This is the final result:
Deleting crosses can be seen as minor discontinuity. A better idea is to bend a vertically flipped chunk of crosses into the 2nd and 4th quarter. It's easy:
duplicate the distorted pattern
release the Envelope distortion
flip or rotate 180 degrees the crosses
re-distort; use Envelope distortion > Make with top object, the released mesh still works if there's made no dimensions nor outline affecting edits.
Another way to make it better is to use 2x2 mesh. It makes possible the bulged appearance at 9 and 3 o'clock on the zero.
NOTE: You can make the mesh denser during the job. Simply click with the Mesh tool the pace of the new mesh crossing. Click an edge if you do not want a new full 4 branch node. Inserted part adapts automatically to already tweaked mesh. As well you can remove an unwanted mesh node. Select the unwanted node with the direct selection tool and press DEL.
As the third enhancement I would tile the crosses horizontally with constant gaps. Placing them with constant distances from center to center looks too sparse at the edges.