From "The Man who Wrote Hatikah" by Ethel Lithman (Cazenove,1979),pp.84-85,
"the viewpoint of Zvi Mayerovitch carries weight, (he)...was at one period lecturer in Jewish Liturgical Music at Jew's College, London. In his opinion the melody of Hatikvah is based on a Sephardi synagogue theme for Hallel, Psalm 117."
She goes on to the Vltava/Smetana idea. Smetana met a Jewess, Frojda Bennecke, niece to a cantor friend of Smetana's in Gothenburg. Through her, Smetana became aware of Jewish liturgical music. Lithman wonders if Smetana incorporated the Sephardi theme as an expression of esteem for Frojda.
In John Clapham's book on Smetana, he says when the tune "resembles but also differs from" a Swedish song, one that he was familiar with. When Smetana's tune turns to the major, it begins to resemble many folk tunes, including 'Twinkle, twinkle,little star', but is closer to Moravian, Slovene and German songs and even closer to a Czech nursery rhyme, "but his Vltava theme, which is in 12-8 time, not 4-4 like all the tunes it resembles, has greater sophistication than any of them."
Clapham's little book doesn't make reference to the possible Jewish connection to Vltava.