tesha

The Hebrew word for nine is tesha (pronounced more like "taysha") תשע, and the masculine form is tisha תשעה (as in Tisha B'Av). Philologos discusses the masculine / feminine forms here, along with a joke about:

newly religious Israeli who informs his boss that he isn't coming to work the next day because it's "Tesha be'Av."

He (who is he? she?) uses this column to present a theory about why numbers have a different gender pattern than nouns, verbs and adjectives:

The reason for this odd turnabout, which exists in Arabic and other Semitic languages as well, is obscure and goes back to the prehistory of the Semitic family. A hint can perhaps be found in certain languages of the Cushitic group, a large family in the Afro-Asiatic phylum to which Semitic belongs. There are some Cushitic languages in which nouns have the gender of their adjective reversed when they go from the singular to the plural. Thus, for instance, in Sidamo, a language spoken in the highlands of East Africa, the adjective ko, "this," is used with a singular masculine noun and te, "these," with a masculine plural, whereas the order is reversed with feminine nouns, te modifying the singular and ko the plural. Something similar seems to have affected the numbers in proto-Semitic.

I have to admit, I don't entirely understand it myself.

As I've mentioned earlier, I don't think that the words for most numbers in Hebrew derived from earlier sources. But Strong does provide an interesting theory:

perhaps from sha'ah through the idea of a turn to the next or full number ten

I suppose this would be similar to the Roman numeral IX being nine - almost ten. According to Steinberg שעה sha'ah has it's roots in the word תעה, meaning to become lost. He defines שעה as to look around, turn from place to place. Steinberg says it is the source of שעשע - to take delight (although Klein does not agree.) In modern Hebrew, we have the derivative hashaya השעיה - "suspension, temporary removal".

Sha'ah meaning "hour" is unrelated.