Is it? You can see from the picture you posted that the glyphs of the digits from Gwalior have as strong resemblance to contemporary 1, 2, 3, 4/5, 7, 9, and 0 (the 4/5 relation is similar to the evolution of English letters like J, G and Y from the Phoenician/Greek letters) while the current Arabic digits, the east Arabic of that chart, are mostly quite different.
