There's some benchmark numbers in the books for different areas. Lousiana itself is covered in "New Orleans by night", but I will include the other areas from the Rage series for completeness:
New Orleans by Night
Lafayette is a Black Spiral Dancer hive, with influence going out to Morgan City. New Orleans itself is a Kindred-controlled town in the West, Garou (Glasswalkers, Bone Gnawers & Uktena) in the Northeast, and Ratkin in the South. The Garou of the area outside the town are mostly Uktena, a few Mokolé live close by and the river delta is, as already said, claimed by Ratkin. There's an official demarcation line to the Kindred: Inner Harbor Navigation Canal and the Intercoastal Waterway form a well visible and easily observable border.
No exact numbers are given.
Taking that into account, and the other books below, a number of about 200-300 Garou in all of Lousiana, including Black Spiral Dancers sounds good. Of them, I estimate some 30-odd Gnawers and 20-ish Glass Walkers inside New Orleans, maybe 20 Dancers plus their allies in the swamps west. The distribution might be "borrowed" from Vancouver or New York, who give numbers down to tribe level, but modified to make the largest tribe the Uktena.
Dark Alliance Vancouver
In total, there are over 360 Garou in B.C. [...] Of these Lupines perhaps 161 live within 20 miles or so of Greater Vancouver's boundaries. No more than 54 Bone Gnawers and Glass Walkers live inside the city limits. p.54
The book goes on to break down each tribe to a minimum number.
Rage across the Amazon
At one point, 190 Garou were fighting Pentax in the Amazon, but casualties have reduced the number to 130. p.39
That's for about 1993. There are also 22 Balam and 33 Mokolé in the area.
Rage across Appalachia
Southern Appalachia usually had between 150 and 200 Garou until 1997, when 50 Garou died in one day. No tribe breakdown is given. There's also a couple of Gurahl (among them an Elder), four Pumonca, a single Kitsune, and at least one Ananasi.
Rage Across Australia
There were at least 350 Garou in 1994 Australia, with known tribal distribution.
Rage across Egypt
Egypt holds relatively few Garou p.87
All of the Changing Breeds still surviving have members in Africa - and possibly in Egypt - save one. The Gurahl[...] p.113.
Among the Fera, the Bubasti are the 3rd most numerous in Egypt but are outnumbered by Garou still. The top number, above all others, is - like always - Ratkin. No other numbers are given.
Rage across New York
New York State has usually about 373 Garou Inhabitants with 335 permanent residents, at least 89 inside New York City. The exact numbers can be found in the book.
Rage across Russia
There were at least 912 Garou in all of Russia before the 1996 attacks by Baba Yaga forces that killed at least 40 Garou. The tribal breakdown is known.