This follows closely the Polish/Slavic usage of present tense for such sentences: Mieszkam tu już of pięciu lat.
In addition, the progression of tenses, which in Esperanto differs significantly from that of the Western tongues, can be seen as being influenced by Polish/Russian usage. Whereas in English, the tense of the verb in the subordinate clause depends on the tense of the verb in the main body of the sentence, as in:
I know that he will come…
I knew that he was going to come...
In Esperanto, as Harlow explains, for subordinate clauses beginning with ke (‘that’) and ĉu (‘whether’) the tense of the verb in the subordinate clause is independent of the main clause:
Mi scias, ke li venos...
Mi sciis, ke li venos...
This too is much in keeping with the way subordinate clauses operate in Polish (Wiem, że on przyjdzie / Wiedziałem, że on przyjdzie – the verb in relative clause stays the same). And it contrasts sharply with the common experience of Poles learning English, for whom progression of tenses is a hard nut to crack.
According to Professor Żelazny, Slavic impact on the Esperanto verb system is further implied in prefixes added onto verbs which sometimes modify the verb aspect, a phenomenon known from the Slavic verb system. Like in kanti vs. ekkanti, where the latter has a perfective aspect.
Phonetics
Another area of a possible Slavic influence is phonology. As Walter Żelazny explains: “The Esperanto phonological system is almost entirely Polish.” That’s why, as Żelazny claims, the majority of Poles, as the majority of Slavs, should not have to learn any vowels. In fact, all the sounds which you can find in Esperanto are also in Polish, including diacriticical signs: ĉ (Polish cz), ĝ (dż), Ĵ (ż), Ŝ (sz), ŭ (ł).
Alphabet
A bit surprisingly, Polish influence is also traceable in the Esperanto alphabet and orthography. The Esperanto alphabet consists of 28 letters, with each letter standing for one sound. Apart from diacritical letters, its peculiarities include the letters C and J. Pronounced as ‘ts’ and ‘y’, respectively, they may at first seem a bit counter-intuitive for many Esperanto learners, but they are best explained on the grounds of the Polish alphabet. It is a common experience of many Polish learners that these letters to the English eye are false friends. (As to further Slavic influence in the Esperanto alphabet, compare the letter ŭ in Esperanto and Belarusian).
Accent